same here, 2021.2.10f1

this happens to me on Unity 2021.2.4f1 every time I export for WebGL. Killing the child process mono.exe that holds the SimpleWebServer.exe task allows it to continue closing

Unity 2021.2.6f1 Editor freezes every time in batchmode with -quit param with text
"Cleanup mono"

If I kill JDK process then Editor continue closing

for me this happens after updating to Unity 2021.2.2 when I want to end the Unity editor.

for me this happens after updating to Unity 2021.2.2 when I want to end the Unity editor.

Same result, differents cause for us.

Use Unity in batchmode (with -quit), call it twice in the same script, the second call will freeze after "Cleanup mono" (no performance report).

Reproduced with Unity 2020.2 & Unity LTS 2020.3, last patch on Win10.

Workaround for us: Add a sleep between the two calls (30s)

Was fine until now with 2018.4

Using 2018.4.29f1 and experiencing the same issues.
It happens very rarely (1 out of 30 times is a good guess) but completely messes up our backend pipelines as lots of bundles need to be built headless using jenkins on a windows server.

Tried to refresh the asset database prior to quitting, tried to quit explicitly using EditorApplication.Quit, nothing works. Editor keeps running and builds never end.
In the log file the last line is "Cleanup mono", nothing out of the ordinary in the logs despite that.

I am having this issue for a while now, including in older unity releases (down to unity 5.6) and it keeps getting back. If its caused by our code that is fine but we have no way to debug this, no information in the log, no unusual warnings, nothing. Any help would be greatly appreciated but I honestly doubt unity knows how to fix it as they are not even capable of reproducing themself.

We had this issue happening but found out it was caused by code in our project that used reflection to access internal editor classes UnityEditor.LogEntries and UnityEditor.LogEntry. Turns out these classes were updated in newer Unity version which caused the reflection to break and now incorrect usage of the LogEntries methods caused Unity to start logging assertion failed messages "Assertion failed on expression: '!m_IsGettingEntries'" and when quitting the editor it would freeze with "Cleanup mono" being the last line of editor log.

Of course this might not be the only way to cause this freezing issue but if you do experience this please check your logs for any unusual error messages and search your codebase if it uses UnityEditor.LogEntries via reflection

We are also seeing the editor hard lock - for us though we don't even need to build. We just load up the editor, run our game, quit the game and then quit the editor. Started happening after upgrading from 2018.4.23 to both 2018.4.26 and 2018.4.27

Last lines of the log are:
[Package Manager] Server::Kill -- Server was shutdown
Cleanup mono