What is What is UnityExtensions ?

When i updated my project from 5.4.3f1 to 5.5.0f3, some errors appeared in the console :
InitializeUnityExtensions: Must have a valid path for plugin

Extension was not registered, that means it relies on default UnityExtensions settings, please register extension and apply neccessary settings for it in the callback.

Each of them are repeted 10 times. When I start playing in the editor, even with all scripts disable, the editor disappear without giving me the possibility to report this bug.

Delete the “Library” - directory and reopen the project has worked for me.

Re-import all assets seems to fix it for me from project right click menu

same here