> For the complete documentation index, see [llms.txt](https://cover-docs.diffblue.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://cover-docs.diffblue.com/updates-and-upgrades/release-archive/2026-04-01.md).

# 2026-04-01

This release adds support for IntelliJ IDEA 2026.1 and removes support for 2025.2.

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## Important Notices

* **Removal of IntelliJ IDEA 2025.2 Support:** Support for IntelliJ IDEA 2025.2 has ended. To use Diffblue Cover plugin version `2026.04.01` onwards, users must upgrade their IDE to IntelliJ version 2025.3 or 2026.1.

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## Enhancements

* Plugin: Diffblue Cover now supports IntelliJ IDEA versions 2025.3 through 2026.1. Users currently running IntelliJ IDEA 2025.2 will need to upgrade their IDE to a supported version to continue using the plugin and receiving new features. \[Ref: TG-24171]

## Known Issues

* Plugin: Diffblue Cover incorrectly displays a menu option to write tests for existing test files. \[Ref: TG-17163]
* Using JDKs other than the supported Open JDK and Oracle JDK may produce unexpected results due to implementation differences. \[Ref: TG-19345]
* Cover may encounter an `F009` (Internal error) caused by a `ClassCircularityError` involving `org/mockito/configuration/MockitoConfiguration` when writing tests with Mockito 5. The recommended workaround is to downgrade to Mockito 4.x. \[Ref: TG-19610]
* Reports: The total line count metric in Reports only includes Java code. Kotlin code is not included. \[Ref: TG-22088]
* Reports: Total lines of code metric can incorrectly count a multi-line comment at the end of a line of code, resulting in fewer than expected lines counted. \[Ref: TG-22089]
* Reports: Following an upgrade, the 'Total Lines of Code' card may show 0 until a new reports bundle has been uploaded. \[Ref: TG-22094]
* Cover may write more simplistic tests with less meaningful assertions when Spring Boot dependency injection is disabled. \[Ref: TG-22102]
* In some circumstances, Cover will still write Spring Boot tests when Spring Boot dependency injection is disabled. \[Ref: TG-22103]
* Cover may write failing TestNG tests when Spring Boot dependency injection is disabled. \[Ref: TG-22107]
* Plugin: On some displays, the Test Review subsection title 'Tests for review' is malformed. \[Ref: TG-22805]
* When test formatting settings are changed, the Test Review feature may incorrectly remove the `@ManagedByDiffblue` annotation from tests, particularly in cases involving static import formatting changes. \[Ref: TG-23750]
* Plugin: Using the Test Review feature may create tests that have incompatible dependency injection systems. \[Ref: TG-23935]
* CLI: In rare circumstances, Cover may remove existing tests when using merge mode (`--merge`). The recommended workaround is to use the `@WriteTestsTo` annotation to specify a separate test class. \[Ref: TG-24166]
* Plugin: When writing tests for a project that targets a JDK version newer than IntelliJ's runtime JDK (e.g., Java 25 with IntelliJ's bundled Java 21), generated tests may not match the project's non-default formatting style and will instead use default IntelliJ formatting. \[Ref: TG-24168]