Knowledge Base > Troubleshooting > Output codes
Meaning of Diffblue Cover output codes.
The possible codes are described below:
- E - Environment codes
- L - Licensing codes
- R - Reason codes
- T - Testability codes
- V - Validation codes
E - Environment codes
|E001||Failed to insert a test||Diffblue Cover failed to write a test in the test Java file. Please enable read and write permissions on the file.|
|E002||Failed to overwrite the created test Java file||Failed to overwrite the created test Java file. Please enable read and write permissions on the file and its parent folder.|
|E003||Failed to read existing test Java file||Failed to read the existing test Java file. Please enable read permissions on this file and its parent folder.|
|E004||No methods found to test||Diffblue Cover was unable to find any methods that can be tested in your selection.
Ensure that your selection includes some Java code that contains methods
that are not private.
If using the
|E005||Parent module without classes||You must run
|E006||JUnit Jupiter Launcher not found||Diffblue Cover cannot verify the generated tests because the JUnit Jupiter Launcher was not
found. We have detected that you have JUnit Jupiter on your classpath but were not able run a
dummy test. Because of this, Diffblue Cover has disabled test verification.
Please ensure that your build system is configured to run JUnit Jupiter tests (for Maven
projects, ensure the Surefire plugin is configured to run JUnit Jupiter tests; for Gradle
projects, ensure that
|E007||Missing classes detected||Diffblue Cover could not execute a Dummy Test in your project. A number of classes were detected as missing. Because of this Diffblue Cover will not be able to verify tests. Please resolve these missing classes to enable test verification.|
|E008||Missing a critical JUnit Jupiter class||Diffblue Cover was not able to run a dummy test in your environment because the
|E009||Unexpected launcher detection output||While trying to detect the path to the JUnit Jupiter Launcher, we detected multiple lines of output where we expected only a single line. Because of this Diffblue Cover will not be able to verify tests.|
|E011||Failed to run a simple example test||Problems in the local build system have been detected that will prevent Diffblue Cover from verifying and validating the created tests.|
|E012||Error when using build system||An error occurred when using the build system. Check the user log file in
|E013||Compatible launcher not found||Diffblue Cover was not able to find a JUnit Jupiter Launcher compatible with your configured JUnit Jupiter Engine. Please adjust your build configuration to use compatible JUnit Jupiter Engine versions. Because of this, Diffblue Cover will not be able to verify tests.|
|E014||No build system found||Neither Gradle nor Maven build systems were detected.
|E015||Specified build system not available||The specified build system is not available. Make sure a build configuration
file for the specified build system is available in the project, or enable
auto-detection of the build system by dropping the
|E016||Failed to connect to analysis service||Make sure that local firewall settings allow connecting to a service at HOST:PORT.|
|E017||Trace loading error||Failed to load execution trace. Please review the cause message to diagnose the underlying issue.|
|E018||Working directory does not exist||The specified working directory does not exist.
Make sure you have specified an existing directory when using the
|E019||Failed to create .diffblue directory||Diffblue Cover failed to create its
|E020||Failed to start up analysis service||Please see Working with code E020.|
|E021||Multiple 'settings.gradle' files||There are multiple
|E022||JUnit Jupiter Launcher location||Diffblue Cover was not able to discover the path to the JUnit Jupiter Launcher. Because of this Diffblue Cover will not be able to verify tests.|
|E023||A file could not be deleted||The given file could not be deleted. If deletion is necessary, please do this manually.|
|E024||Multiple files could not be deleted||The given files could not be deleted. If deletion is necessary, please do this manually.|
|E025||Unable to download the launcher||Diffblue Cover uses the JUnit Jupiter Launcher to run verify tests. While attempting to download the launcher we encountered an error. Because of this, Diffblue Cover has disabled test verification.|
|E026||Custom validation command unsuccessful||Diffblue Cover was not able to execute the custom validation command successfully and has disabled test validation.|
|E027||JUnit Jupiter Engine not found||Diffblue Cover was not able to find a JUnit Jupiter Engine configured in your project's dependencies. Diffblue Cover uses this to determine the version of the JUnit Jupiter Launcher to use when verifying tests. Please ensure that your project is configured to run JUnit Jupiter tests. Because of this, Diffblue Cover will not be able to verify tests.|
|E028||Cannot determine dependencies||Diffblue Cover was not able to determine the dependencies of your project. Check the build system output in the user log file for further information. Because of this Diffblue Cover is not able to verify tests.|
|E029||Invalid trace directory||Failed to select a trace from the trace directory. Please review the cause message to diagnose the underlying issue.|
|E030||Test creation cancelled||Test creation for this method was cancelled as requested.|
|E031||Unsupported Java language version||We recommend you change your module settings to JDK 1.8, JDK 11, or JDK 17.|
|E032||Failing tests detected while validating||Diffblue Cover tried to validate the tests it created but failed due to failing tests. Diffblue Cover cannot fix this problem automatically. The output from running the validation command is available towards the end of the log file. Please see our documentation for further guidance.|
|E041||Failed to apply refactoring||Failed to apply refactoring. Check the build system output in the user log file for further information.|
|E042||Failed to write refactoring config file||Failed to write refactoring configuration file. Please enable write permissions on this file and its parent folder.|
|E043||Failed to install into Maven repository||Failed to install a file into the local Maven repository. Make sure the displayed command can be executed successfully.|
|E044||Incompatible user options||The two given options are incompatible. Remove one of them.|
|E045||Validation command failed for unknown reasons||Diffblue Cover tried and failed to validate the tests it created. The output from running this command is available towards the end of the log file. While Diffblue Cover could not figure out the reason for this and cannot fix it automatically, this issue is usually due to an incorrect validation command, or due to the failure of existing, user-provided tests. Please see our documentation for further guidance.|
|E046||Failed to load Maven settings||Failed to load Maven settings.xml files from the user's home directory or maven installation directory. Make sure that Maven commands can be executed successfully, using your settings.|
|E047||Unsupported Java version||Please use Java 8 Update 261+, Java 11 (but not version 11.0.7) or Java 17.|
|E048||Invalid JaCoCo report file||Diffblue Cover was unable to read the given JaCoCo report file.|
|E049||inotify limit too low||The current inotify watch limit is too low. Try restarting the IDE and/or your machine. Check your inotify limit and consider resetting to a higher value.|
|E050||Unsupported tool version||Unfortunately the version of the specified tool you are using is unsupported. Please consider upgrading.|
|E051||Current JVM does not support JDK which compiled the project||Diffblue Cover needs to be executed with the same or a more recent Java version than the version with which the project was compiled.|
|E052||Missing dependency||Required dependencies were not found. Please add these dependencies.|
|E053||Unsupported dependency||A dependency was found at an unsupported version. Please upgrade it to the given version.|
|E054||No class files found||Diffblue Cover could not find any .class files for your project. This usually means that your project has not yet been compiled.|
|E055||Failed to compile a simple example test||For Diffblue Cover to run successfully, we require an example test to pass. Please see our documentation.|
|E056||JDK not found||Diffblue Cover requires a JDK (Java Development Kit) to run. A JRE (Java Runtime Environment) is not sufficient.
Diffblue Cover expects the JDK in
|E057||Service startup certificate problem||There was a problem with the SSL certificates used to set up the connection. Check whether you have the full set of CA certificates for Java installed.|
|E058||Service startup I/O problem||There was an I/O problem while trying to set up a network connection to the service. Please check whether you have a firewall configuration that disallows TCP servers on localhost.|
|E059||Service startup message timeout||If your machine is heavily loaded or very slow, try reducing load before running Cover.|
|E060||Service startup SSL problem||Please contact Diffblue Support, providing details about this error.|
|E061||Service startup timeout||If your machine is heavily loaded or very slow, try reducing load before running Cover.|
|E062||Service JVM exited unexpectedly||Please contact Diffblue Support, providing details about this error.|
|E063||Diffblue Cover component missing||A Diffblue Cover component is missing. Please check your installation is complete.|
|E064||Service startup I/O failure||Starting up the service failed because of an I/O problem while trying to execute the JVM for the service process. Please check whether your installation is complete, whether all files are readable and whether the JVM in JAVA_HOME is executable.|
|E065||Service startup interrupted||Please contact Diffblue Support, providing details about this error.|
|E066||Dependency incompatible with JDK||Some dependencies are incompatible with the current JDK (version). Please add the following dependencies to your project (list).|
|E067||JVM not a 64-bit implementation||Diffblue Cover requires a 64-bit JVM to run. A 32-bit JVM is not sufficient.
Make sure a 64-bit JDK 8, 11 or 17 is installed and
|E068||Failed to load custom input rules||Diffblue Cover tried to load custom input rules but was unable to read the content of the file correctly. Please review the content of the custom input file and ensure that it is correct. Information about the input rules format can be found in our documentation.|
|E069||Environment checks failed||Please check your environment. More information on the runtime environment can be found in our documentation.|
|E070||Compilation failed||Diffblue Cover cannot write tests because your project failed to compile. Please ensure that your project compiles successfully before trying to write tests again.|
|E071||Surefire version mismatch||Diffblue Cover detected an old version of the Maven Surefire plugin in use in your project. Because of this Diffblue Cover will not be able to verify tests. Additionally, this version is not sufficient to produce coverage reports. Please upgrade the the most recent version. If you are using JUnit Jupiter 5, you need a minimum of 3.0.0-M7. If you are using JUnit 4, you need a minimum of 2.3.|
|E072||Surefire missing||Diffblue Cover detected an old version of the Maven Surefire plugin in use in your project. Because of this Diffblue Cover will not be able to verify tests. Please upgrade the the most recent version. If you are using JUnit Jupiter 5, you need a minimum of 3.0.0-M4. If you are using JUnit 4, you need a minimum of 2.3.|
|E073||Static mocking is not configured||The
|E074||Mockito test dependency not found||The
|E075||Static mocking is not supported||The
|E077||Invalid trace file found||Unable to load the trace. Please record your application again with the Replay agent of your current installation of Diffblue Cover.|
|E078||Writing report failed||Diffblue Cover tried and failed to write a report. Check to see if you have the correct permissions to write to the file, or use a different path for the report.|
|E079||Failed to create test output directory||Diffblue Cover failed to create the test output directory (e.g.
|E080||Invalid patch file||Diffblue Cover was unable to read the given patch file.|
|E081||Failed to write file||Failed to write the coverage report. Please check permissions.|
|E082||Could not find JaCoCo report||The JaCoCo report could not be found. To troubleshoot, try running the logged command and check that the coverage report is created at the expected location.|
|E083||Error while producing JaCoCo report||The JaCoCo command failed for an unknown reason. Please check the user log file.|
|E084||JaCoCo command failed||The JaCoCo command returned a non-zero exit code. Please check the user log file. This happens when there are no tests to run. If this is unexpected, make sure JaCoCo is setup in the project.|
|E085||Attempt to compile a test as Groovy||Please ensure the build configuration compiles Diffblue tests as java.|
|E086||Specified test framework not available||The test framework specified is not available on the classpath. Please add it as a dependency.|
|E087||Multiple testing frameworks, select one||There are multiple testing frameworks available in your build configuration,
and it is not clear which of them should be used by Cover.
Please use the
|E088||No supported test framework on classpath||A supported version of JUnit is not available on the classpath.
Please add at least one supported JUnit version to the classpath.
For a Spring Boot project, this should be done by adding
|E089||Can't parse specified test framework||The test framework argument provided is not a valid, supported JUnit version. Please refer to our documentation for the list of supported versions.|
|E091||Failed to load execution policy rules||Diffblue Cover tried to load custom execution policy rules but was unable to read the content of the file correctly. Please review the content of the custom execution policy rules file and ensure that it is correct.|
|E092||Missing embedded database engine||No embedded Java database engines were detected. This will prevent Diffblue Cover from writing
tests for repository classes. Spring supports HSQL, H2, and Derby.
Please add one of these as a dependency to your project.
Alternatively, if you are not interested in testing repository classes, they can be excluded
|E093||jacoco-maven-plugin is too old||The version of the jacoco-maven-plugin is too old to support the prepare-agent and report
goals needed to generate the coverage reports. Please adjust your
To view coverage data in Cover Reports we use the prepare-agent and report goals of the
|E094||jacoco-maven-plugin doesn't produce XML||The jacoco-maven-plugin is not configured to produce the XML output format.
Please add XML to the list of <formats> in the configuration, e.g.
... <plugin> <groupId>org.jacoco</groupId> <artifactId>jacoco-maven-plugin</artifactId> <version>0.8.7</version> <configuration> <formats>HTML,XML</formats> </configuration> <executions> <execution> <id>jacoco-initialize</id> <goals> <goal>prepare-agent</goal> </goals> </execution> <execution> <id>jacoco-site</id> <phase>test</phase> <goals> <goal>report</goal> </goals> </execution> </executions> </plugin> ...
The XML coverage report is used by Cover Reports to show the coverage produced by Diffblue Cover alongside the developer written tests.
|E095||Project properties set to skip JaCoCo||Tests were generated, but we couldn't measure the coverage.
This is because a
|E096||Required file missing for upload||One of the report files was not available when we tried to upload them to Diffblue Cover Reports. This can be caused either by the reports not being created, or being moved before the upload started. See working with Cover Reports for more information.|
|E097||Cover Reports server connection problem||We couldn't connect to the Diffblue Cover Reports server. This could be due to a wide number
of reasons, for example:
|E098||Diffblue Cover Reports server error||The Diffblue Cover Reports server was not able to process the upload request. Please contact Diffblue Support.|
|E099||Cover Reports upload was successful||The upload was successful.|
|E100||Cover Reports upload was successful||The upload was successful.|
|E101||Cover Reports upload status unknown||The upload was unknown because we didn't get a response from the server to indicate whether the upload was successful. Check your reports and see if the upload succeeded, if not, please try again. If you believe this is a problem, please contact Diffblue Support and provide this message along with the logs.|
|E102||Cover Reports upload was successful||The upload was successful but the server sent a response we were not expecting. Please check your logs and contact Diffblue Support if you believe there is a problem.|
|E103||Gradle project root not found||Diffblue Cover was unable to find the root of your gradle project. Check the
user log file in
|E104||Mockito failed to initialize||Mockito failed to initialize for some reason. Likely resulting from a dependency mismatch. Review the quoted message and address the concerns in order to create tests using mocks.|
|E105||No active Spring profile specified||This project uses Spring profiles but no profile was supplied through the
|E106||Multiple versions of dependencies||Multiple versions of dependencies for the same Spring group. Diffblue Cover may not be able to create Spring tests correctly. Consider reducing the number of dependencies.|
|E107||Incompatible Spring dependency||The dependency is not compatible with
|E108||Invalid method specification||Invalid method prefixes were specified by the user.|
|E109||Max heap size too low||Diffblue Cover running without sufficient memory allocated.
Please use the
|E110||Timeout running a simple example test||Problems in the local build system have been detected that will prevent Diffblue Cover from verifying and validating the created tests.|
|E130||Invalid characters in template||The template must only use valid Java identifier characters (a-z,A-Z,0-9,$,_) and must not start with a digit. Remove the illegal characters.|
|E131||Unterminated variable in template||The template contains an unterminated variable (
|E132||Invalid variable in template||The template contains an unrecognized variable. Remove this variable.
In class templates only
|E133||No variable in template||The template does not contain any variable to include the class or method name.|
|E134||Only variable in template||The specified class name template consists only of the variable
|E135||Class name too long||The specified class name template has too much static text (more than 128 characters). This would probably lead to class file names too long to store on disk.|
L - Licensing codes
|L003||Too many methods marked for analysis||Writing tests for these methods could use up your remaining budget of tests. Consider writing tests for a single class or method at a time so that the number of methods to write tests for is less than your budget limit.|
|L004||License activated too many times||Your license has been activated too many times. Please contact either your license administrator or Diffblue Support.|
|L005||The license has expired||Your license has expired - please contact your license administrator or purchase a new one on our pricing page.|
|L006||Exceeded license limitations||You have exceeded the limit for your license. Please contact either your license administrator or Diffblue Support, or see our pricing page for information on increasing the limit.|
|L007||The license is not active||Your license is not active. Please contact either your license administrator or Diffblue Support.|
|L008||The license is not enabled||Your license is not enabled. Please contact either your license administrator or Diffblue Support.|
|L009||License key not found||Please check that the license key you entered is correct. If you still have problems, please contact either your license administrator or Diffblue Support.|
|L010||License server unreachable||Check that you have an active internet connection and that any firewall rules
allow outbound connections to
Diffblue Cover Enterprise Edition supports offline activation and offline use.
|L011||Failed to encrypt/decrypt license file||The installed Java version does not provide the required cryptographic algorithms. Please install a newer version of the JDK.|
|L012||Unable to verify license||Either your licence file has expired, it has been corrupted, or you are activating an offline license response with the wrong key. Please contact your license administrator or Diffblue Support.|
|L013||Features not available with this license||Some features are not available with your version of Diffblue Cover. Please contact your licence administrator or see here for information on our editions and on upgrading.|
|L014||Activation required||You have not activated your licence yet. For the CLI, run
|L015||License is read-only||Ensure your license file can be written to.|
|L016||Hardware configuration has changed||Computer hardware configuration has changed or the license does not belong to
For the CLI, run
|L017||Failed to activate Community Edition||Diffblue Cover was unable to obtain a Community Edition license. Please try again later or contact Diffblue Support.|
|L018||Licensing server SSL certificate error||This indicates that something between your machine and the licensing server is intercepting your connection. This is usually caused by some sort of firewall configuration. For help, please contact your license administrator or Diffblue Support.|
|L019||Offline mode not supported by license||You have attempted to run Diffblue Cover in offline mode, however that
feature is not supported by your current licence.
Delete the offline license directory to return to online mode.
Only Diffblue Cover Enterprise Edition supports offline activation and offline use.
|L020||Offline license has not been activated||An offline license is present but has not yet been activated.
Only Diffblue Cover Enterprise Edition supports offline activation and offline use.
|L022||Offline mode not reset||You have deleted your offline license file,
however you have not properly restarted your IDE.
Please close all IDE windows and ensure your IDE is fully exited before restarting.
R - Reason codes
(reasons for tests not being created that may have a work around)
|R002||Missing observers||There are no fields that could be asserted on. Add getters or make the fields package-private.|
|R005||Unable to load class||Please check that the class is available on your test runtime classpath. See our documentation for further guidance.|
|R006||Static initializer failed||A static initializer threw an exception while trying to load a class. Make sure static initializers can be executed without throwing exceptions.|
|R007||Class not accessible||Make sure all classnames are accessible from their targetPackage, for example by making them public.|
|R008||Failed to instantiate class under test||Diffblue Cover was unable to construct an instance of
See Working with code R008 for further troubleshooting of this issue.
|R011||Sandboxing policy violation||Diffblue Cover's default sandboxing policy disallowed test writing in order to prevent your code from damaging your system environment. Please see Working with code R011.|
|R012||JNI sandbox policy violation||Diffblue Cover ran code in your project that tried to load a JNI library, violating the default security policy. See Java Native Interface to resolve this issue.|
|R013||No inputs found that don't throw a trivial exception||Diffblue Cover tried to run the arrange/act section, but the method under test threw an error. Add constructors or factory methods that make it easier to construct fully initialized objects. Please see Working with code R013.|
|R018||Trace file incomplete||The method under test could not be found in the execution trace. The trace file was only partially loaded because an error was found while loading it. Please record your application again with the Replay agent of your current installation of Cover.|
|R019||Method not in trace||The method under test is not called in recorded execution trace. Record your program again and provide program inputs that trigger at least one call of the method under test.|
|R020||Temporary files were created but not deleted||Please ensure that temporary files are deleted in the method under test.|
|R021||Missing Spring component||Diffblue Cover detected Spring on the classpath, but failed to load critical components while building the Spring context. Make sure these components can be loaded.|
|R023||Out of memory||Diffblue Cover failed to create tests because it ran out of memory.
See: Memory Management
|R026||Failed to create Spring context||Failed to create Spring context. Check to see if there are any missing environment variables or system properties. For detailed and further troubleshooting please see Working with code R026.|
|R027||Missing beans when creating Spring context||Failed to create Spring context due to missing beans. Check to see if there are any missing environment variables or system properties. Also missing beans could be defined in Spring profiles that aren't used for test generation. Otherwise, please contact Diffblue Support with details of the entire output message and the source code of the class under test.|
|R028||Incomplete repository information||Try extending CrudRepository with concrete type parameters, or if the class
should not be considered a repository then annotate the class with the
|R031||Method may be time-sensitive||Please see Working with code R031 for details.|
|R032||User requested skeleton tests only||Information only.|
|R033||Missing Spring properties||Some classes in the Spring context have @Value annotation that Diffblue Cover
can't resolve. Usually variables for such annotations are provided in
|R034||Diffblue Cover can't complete test||Diffblue Cover needs to run a number of construction steps to create a test. If the number
of steps allowed when setting
|R074||Unable to create static mock||Mockito was unable to create a static mock for a class. Please review the underlying cause in the output message or log.|
|R081||Exception in arrange section||Diffblue Cover was unable to construct an instance of the class under test because a step in the arrange section threw an exception.|
|R082||Can't create a parameter for constructor||Diffblue Cover was unable to construct an instance.
Diffblue Cover failed to create a parameter for the constructor or factory method call.
|R083||Can't find a suitable constructor||Diffblue Cover was unable to construct an instance.
No suitable constructor or factory method found. Please check that the class under test has a non-private constructor or factory method.
|R084||Enum has no constants defined||Diffblue Cover was unable to test an instance of an enum as no constants are defined.|
T - Testability codes
|T000||Should be tested directly||Information only.|
|T001||Trivial getter||Information only.|
|T002||Trivial setter||Diffblue Cover will not attempt to create a test for this method. It may be tested indirectly.|
|T003||Private method||The method is declared private or in a private inner class. It cannot be called from another class in the same package. Diffblue Cover will attempt to test it indirectly through other callable methods. If you want to test this method directly make it package-private.|
|T004||In anonymous inner class||The method is declared in an anonymous inner class. It cannot be called directly. Diffblue Cover will attempt to test it indirectly through other callable methods. If you want to test this method directly, factor out the anonymous class into a package-private class.|
|T005||Trivial constructor||Diffblue Cover will not attempt to create a test for this constructor. It may be tested indirectly. Default constructors of static utility classes are considered trivial.|
|T006||Main method||Refactor the main method. E.g. factor out its body into a separate, accessible method that returns the results that should be asserted on.|
|T007||Framework configuration callback||Certain framework callbacks should not be directly tested because of possible side effects. Diffblue Cover will attempt to test indirectly through other callable methods.|
|T008||Private and never called||The method cannot be called from another class in the same package. It is not called by any other method and therefore cannot be tested. If the method is dead code then remove it from your code base.|
|T009||No implementation for abstract class||The method is a non-abstract instance method in an abstract class or a default method in an interface. Diffblue Cover would test such methods by using an implementation of that abstract class or interface. However, no such implementation has been found. Please provide an implementation for the abstract class or interface.|
|T010||Abstract or interface method||Information only.|
|T012||Synthetic method||Indicates that the method is synthetic. Currently, this includes methods:
|T020||Other trivial method||Information only.|
|T021||Empty method body||Diffblue Cover will not attempt to create a test for this method.|
|T022||Cannot test mocked method||The method under test is not unit-testable because it must be mocked.|
|T023||Testability unknown||Indicates that the testability could not be determined for the method. Diffblue Cover considers these methods as not testable.|
|T033||Method excluded from test creation||Diffblue Cover did not create tests for this method as the user chose to exclude them.
If you wish to have tests created for this class, please check that it is not within the
V - Validation codes
|V003||Tests discarded during validation||Please see Working with code V003 for further details.|