Knowledge Base > Troubleshooting > Output codes

Output codes

Meaning of Diffblue Cover output codes.

The possible codes are described below:

E - Environment codes

Code Meaning Suggestion
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 --patch-only option, ensure that the patch file was created correctly and that its encoding is UTF-8.
E005 Parent module without classes You must run dcover on the individual submodules. Use dcover create --working-directory path/to/submodule or change into the submodule directory and run dcover create from there.
E011 Failed to run a simple example test Problems in the local build system have been detected that will prevent Diffblue Cover from verifying the created tests.
E012 Error when using build system An error occurred when using the build system. Read the output of your build system below to fix the problem. Also, check the log file in .diffblue/log which contains the entire build system log to find the build system error message.
E014 No build system found Neither Gradle nor Maven build systems were detected. Use the --classpath option or CLASSPATH environment variable to specify a classpath manually.
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 --gradle or --maven options you might be using.
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.
E020 Failed to start up analysis service Please see Working with code E020.
E021 Multiple 'settings.gradle' files There are multiple `settings.gradle` files in your project, which may cause your project configuration to be invalid. Consolidate the content of your `settings.gradle` files into a single file at the root of your project, and remove all other `settings.gradle` files.
E030 Test creation cancelled Test creation for this method was cancelled as requested.
E041 Failed to apply refactoring Failed to apply refactoring. Check the build system output in the 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 161+, Java 11 (but not version 11.0.7) or Java 17.
E048 Mismatched test dependency Test dependencies were found at a version that does not match other dependencies. Please upgrade the following dependencies to the given versions.
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 test dependency Required test dependencies were not found. Please add these dependencies.
E053 Unsupported test dependency Test dependencies were found at an unsupported version. Please upgrade the following dependencies to the given versions.
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 RT_JAR_PATH or JMODS_PATH. Make sure a JDK is installed in these locations.
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 supported dependencies were not found or were 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 JAVA_HOME is set to its installation location.
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 Missing Maven plugin Please check that the specified Maven plugin is installed correctly.
E073 Static mocking is not configured The --mock-static option was specified, but your project has not been configured to use the Mockito inline mock maker. Mockito recommends placing the 'mockito-inline' artifact where you are currently using 'mockito-core'.
E074 Mockito test dependency not found The --mock-static option was specified, but Mockito is not present in your project. Please add Mockito to your project as a test dependency.
E075 Static mocking is not supported The --mock-static option was specified, but your version of Mockito is not sufficient to support static mocking. Please upgrade your version of Mockito to at least version 3.4.0.
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.
E080 Patch file not found Please check that the (absolute) path to the patch file is correct.
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 log file.
E084 JaCoCo command failed The JaCoCo command returned a non-zero exit code. Please check the 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 --testing-framework option to select a testing framework, e.g. --testing-framework=junit-4 or --testing-framework=junit-5.
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 the spring-boot-test dependency.
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 using the --exclude option.
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 pom.xml to use version 0.8.7.
To view coverage data in Cover Reports we use the prepare-agent and report goals of the jacoco-maven-plugin to record the coverage as the tests are executed. These goals are not available in your currently configured version of the plugin.
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 jacoco.skip property is being set to true in the pom.xml of the project under test. Please remove this property, or set it to false to measure the coverage.
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 https://docs.diffblue.com/knowledge-base/cli/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:
  • Cover Reports isn't running, or the server is down
  • The Cover Reports hostname is not able to be resolved
  • There's a firewall blocking the connection between the machine and Cover Reports
  • The connection between the client and the server is too slow
If you were running as part of the 'create' command you can use 'upload' to avoid recreating all the tests. If you are still experiencing problems, please contact Diffblue Support.
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 which can be found in $_logfile.
E102 Cover Reports upload was successful The upload was successful but the server sent a response we were not expecting. Please check your logs at $_logfile 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 log file in .diffblue/log which contains the build system log to find the build system error messages.

F - Failure codes

Code Meaning Suggestion
F001 Internal error Please contact Diffblue through the appropriate support channel, providing details about this error.
F002 Internal error Please contact Diffblue through the appropriate support channel, providing details about this error.
F003 Internal error Please contact Diffblue through the appropriate support channel, providing details about this error.
F004 Internal error Please contact Diffblue through the appropriate support channel, providing details about this error.
F005 Failed to load internal proxy class Please contact Diffblue through the appropriate support channel, providing details about this error.
F006 Failed to extract resource Please contact Diffblue through the appropriate support channel, providing details about this error.
F007 Failed to load internal proxy class Please contact Diffblue through the appropriate support channel, providing details about this error.
F009 Internal error Please contact Diffblue through the appropriate support channel, providing details about this error.
F018 Internal error Failed to extract inputs from recorded execution trace. Please contact Diffblue through the appropriate support channel, providing details about this error.
F019 Internal error Please contact Diffblue through the appropriate support channel, providing details about this error.

L - Licensing codes

Code Meaning Suggestion
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 https://api.licensespring.com and https://licensing.diffblue.com/
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 'dcover activate' with your license key to activate your license. For the plugin, click `Diffblue` and `Activate License` in the menu bar to activate your license. If you do not have a license key then please contact your license administrator or purchase one from Diffblue.
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 this computer. For the CLI, run 'dcover activate' with your license key to activate your license. For the plugin, click `Diffblue` and `Activate License` in the menu bar to activate your license.
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. Run dcover activate --offline to activate your offline license.
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)

Code Meaning Suggestion
R002 Missing observers There are no fields that could be asserted on. Add getters or make the fields package-private.
R004 No meaningful assertions found Diffblue Cover was unable to create an assertion. Make sure that fields modified by the method under test have package-private, protected, or public getters. Please see Working with code R004.
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 someClass. Ensure there is a package-visible constructor or factory method that does not throw for the class under test. If such a method is already present but Diffblue Cover does not find it, it can be specified using custom rules for inputs: custom-inputs
See Working with code R008 for further troubleshooting of this issue.
R010 Timeout Diffblue Cover timed out. This often happens because Diffblue Cover ran code in your project which requests user input (System.in), blocks on a lock, or runs into an infinite or very long loop. Please see Working with code R010.
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.
R015 Method may be nondeterministic The execution of the created test may depend on the runtime environment. Please see Working with code R015.
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_link_html()
R024 Analysis service shutdown unexpectedly Diffblue Cover failed to create tests because the analysis service shutdown unexpectedly. This can sometimes be caused by exceeding available resources (memory, threads, file handles, etc) or by internal errors.
R025 Skipped due to previous failure Diffblue Cover failed to create tests for a method, and thus needed to skip all methods in the class.
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. 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 @NoRepositoryBean annotation.
R031 Method may be time-sensitive Please see Working with code R031 for details.
R032 User requested skeleton tests only Information only.
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.

T - Testability codes

Code Meaning Suggestion
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 this method is called by reflection then annotate it with @SuppressWarnings("unused"). If the method is indeed 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.
T011 Annotated by @SuppressWarnings("unused") The method is probably called by reflection and will not be tested directly. If you want to test this method directly then make it package-private and remove the annotation.
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.

V - Validation codes

Code Meaning Suggestion
V003 Tests discarded during validation Please see Working with code V003 for further details.

W - Verification codes

Code Meaning Suggestion
W001 Test did not compile Diffblue Cover removed the following test because it did not compile. Please contact Diffblue Support, providing details about this error.
W002 Test compiled, but did not pass Diffblue Cover removed the following test because it did not pass when run. Please contact Diffblue Support, providing details about this error.