Ubuntu 18.04
Unity 2017.4.18f1 64bit

9 audio files, all with the same problems:
"Unspecified error during import of AudioClip ..."

solved only with: sudo apt-get install lib32stdc++6

Thanks Maorc1981 for your advice.

as @LONELYFEW said... Unity doesn't like when the file has different dates... for everyone asking how to "touch" the file... if you are on unix (os x, or linux) you can run this command:

$ touch FILE_WITH_PROBLEMS.wav

this will reset the date of the file... you have to do this for every file that unity imported :(

Doesn't seems to be duplicate of that issue (https://issuetracker.unity3d.com/issues/unspecified-error-during-import-of-audioclip) , it reproduces to me on Ubuntu 17.10 Unity editor 2017.3.1.f1 64b mp3 file.

Guys, I had the same issue with Ubuntu 17.10 and Unity 2017.3.0p2 and I managed to FIX it by installing a missing library:

apt-get install lib32stdc++6

BTW, I found the issue by checking the Editor.log. After import I had this error:
FSBTool: error while loading shared libraries: libstdc++.so.6: cannot open shared object file: No such file or directory

Good luck,
Maor

I also have this issue on Ubuntu 17.04 with Unity 2017.3.0p2.
Touching doesn't seem to work.
But some of the files can be fixed by repeatedly importing them. Weird.

On Fedora 27 Unity 2017.30f1 has this issue too.

On Ubuntu 17.10 with Unity 2017.30f1 and I'm still having this bug, all mentioned solutions do not work for me.

what does “Touched” means？？ @JONC113

I have found the problem, it seems that Unity doesn't like it when the 'modified' date of the file is in the future - which can happen when getting assets from other countries.

So this is why the 'touch' or 'COPY /B filename.ext +,, filename.ext' on windows will fix the issue - as it sets the modified date to be in the past.

Had same problem. I "touched" the file and then it imported ok.