Editor.exe hangs when using another System.Collections.Immutable.dll version

The Editor.exe hangs after startup if a plugin, in its own folder, uses a more recent version 5.0.x of the System.Collections.Immutable.dll.
Only the kill of the ‘Keysight Test Automation’ process via the Task Manager is possible.

In the \Dependencies folder of the latest OpenTAP, v9.17.4.0, I see that v4.6.26515.6 of System.Collections.Immutable.dll is used.

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Hi @fostyn

I tested this with OpenTAP 9.17.4 and Editor 9.17.3.

I am not able to reproduce this issue. I see the editor hangs if System.Collections.Immutable.dll is missing, but it seems like it works as expected with version 5.0.0.

Generally, however, you cannot expect everything to keep working normally if you change dll dependencies, becaause they are not guaranteed to be backwards compatible.

Hi @alexander.larsen ,

thanks for checking this out.

We use the latest version of both OpenTAP and the Editor, v9.17.4.

Just tested again on a completely new installation in the folder D:\OpenTap.
In a Subfolder D:\OpenTAP\Plugins it is enough to just copy the System.Collections.Immutable.dll (, it’s not possible to upload this file).
The Editor.exe starts up, but we can’t select or run anything else… the Editor.exe hangs.

Maybe I wasn’t clear enough, but it wasn’t my intention to replace the DLL(s) from the \Dependencies folder.
Our test was to see what happens if we use other versions of pre-existing DLL’s in our own folder (like DLL’s from the \Dependencies folder) !
We know that this can sometimes cause problems but I didn’t expect that the Editor.exe would have problems with this already at start-up.

Hi @fostyn ,

I am copying the exact same version into my installation and I don’t see the error.
I tried with the net461, netstandard1.0, netstandard1.3, and netstandard2.0 versions of the DLL and everything seems to work fine.

Can you upload your session log from a hanging Editor instance?

Here it is:
00.txt (14.3 KB)


Thanks, I am able to reproduce it now!

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FYI I have identified the bug in OpenTAP:

The fix should make it into 9.18


Hi @fostyn,

FYI 9.18 has been released and this issue has been resolved

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