Using JustMock could cause unexpected debugger errors

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Completed

Last Updated: 18 May 2026 13:35 by ADMIN

Release 2026 Q2

Ivo

Created on: 27 Jun 2025 14:07

Category: JustMock

Type: Bug Report

Using JustMock could cause unexpected debugger errors

To replicate the problem using the provided project, follow these steps:

1. Open the solution in Rider.
2. Set breakpoints at the beginning of the test.
3. Start debugging the test.
4. Step into the constructor of the Car class and inspect the contents of the array. Note that if this step is skipped, the issue will not be reproducible.
5. Step out of the constructor.
6. Continue execution until just before calling the virtual function for the Number property.
7. Step into the function.

**EXPECTED** The value of Name should be visible.

**ACTUAL** A debugger error occurs.

The issue can appear in both Visual Studio (showing "Internal error in the C# compiler") and Rider (showing "Read out of bounds").

Attached Files:

reprodebugerror2.zip

2 comments

ADMIN

Valentina

Posted on: 18 May 2026 08:02

Hi, everyone!

Thank you for bringing this issue to our attention and for your patience while we investigated it.

We collaborated closely with the JetBrains Rider team to identify and resolve the problem. We’re pleased to inform you that the issue has now been fixed, and the resolution is included in Rider version 2026.1.1. The fix will also be available in all future Rider releases.

For your reference and full transparency, you can review the corresponding issue in the YouTrack system.

If you encounter any further issues or have additional questions, please don’t hesitate to reach out.

Regards,
Valentina
Progress Telerik

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ADMIN

Valentina

Posted on: 11 Feb 2026 14:55

Hello, everyone!

The issue has been successfully reproduced on our side and occurs only when debugging in JetBrains Rider. It does not appear in Visual Studio, which points to behavior specific to Rider’s debugging engine.

The Rider team has already been contacted regarding this, and a response is currently awaited. Their input should help clarify the underlying cause and whether any adjustments are required on either side.

Although an investigation was initially planned for Q1 2026, a fix could not be completed in that timeframe. The issue remains open and actively tracked, and the thread will be updated as soon as new information becomes available.

Valentina
Progress Telerik

Love the Telerik and Kendo UI products and believe more people should try them? Invite a fellow developer to become a Progress customer and each of you can get a $50 Amazon gift voucher.