Unity stuck on "Importing" while starting Unity 2020

When I start Unity 2020 from Unity Hub it gets stuck on either “Importing” or “Compiling Assembly Definition Files scripts”. So I can’t get into any Unity project.

Try deleting (or moving to your Desktop) the Library folder in the root of your project. It contains Unity’s cache which might be corrupted. Next time you open the project it should take a much longer time than usual to reimport everything.

Same issue here, if I exit Unity via taskbar and relaunch it works back, but, as soon as PC is restarted the issue may reappear.

[Solved] Auro-response:
I found that, the PC experiencing this issue, had a malwhare and, after removing it, everything started to work as usual. So, take a look at your running processes and services and an antivirus scan should help as well.

A corrupted asset can cause this. If deleting Library and opening the project again doesn’t help, then check the Editor logs. Do this after closing/crashing the application and you may be able to find what it’s getting tripped up on. See here: Unity - Manual: Log files under the Editor header to find out where those are on your machine. There have been problems importing various file types in certain software configurations / unity versions / operating systems over the years.

Ooof, don’t delete you meta files. Your library is probably corrupt, delete the Library folder, it will regenerate the database from the metafiles.

Same issue as Jorhoto.

If I kill unity using task manager and relaunch it it works fine but after a PC restart the issue is back.

The title is always “Importing (busy for …)” and the description is always “Importing…”.

Deleting/moving the Library folder has no effect.

I did a diff on the old Library folder and the new one after reimport and they were exactly the same.

Heres the last 6 lines of the Editor.log:

Begin MonoManager ReloadAssembly
Symbol file LoadedFromMemory doesn't match image C:\[ProjectPath]\Library\PackageCache\com.unity.ext.nunit@1.0.0

Native extension for WindowsStandalone target not found
Native extension for Android target not found
Refreshing native plugins compatible for Editor in 1.40 ms, found 13 plugins.
Preloading 1 native plugins for Editor in 0.04 ms.

(the rest of the logfile is normal)

I have found this bug report: https://forum.unity.com/threads/symbol-file-loadedfrommemory-doesnt-match-image.1007294/

But no solution.

A different non-obvious solution to this - my Unity projects were in a Dropbox folder, and Dropbox had moved some files to the cloud to save space on the local SSD. Unity can see the project files but they were empty stubs on the local disk. To make them local, you right click the project folder, choose Smart Sync > Local and wait for them to download.

I fixed this by moving the project folder from a NAS location to my local disk.
Took me an insane amount of trouble to get there, no idea why this fix is not known by Unity staff.

Be ware that it may be an indicated that your system is infected by a malware.