UnauthorizedAccessException in powershell using Clear-Content

It might be in access by AntiVirus software, or another process. Did you check that yet?

Anti Virus is not the problem, I tried that.   Another process - only process that access it is the one that creates it and I disabled that to see if it was causing the problem, no change in outcome.

Is the file local or on a share?
Are you able to delete/change/rename the file manually?
If loacal, check with Process Explorer or handle.exe (both www.sysinternals.com) whether the file is not open anymore. handle.exe might be easier for that purpose, as you just have to provide a part of the filename to get all open handles for that file.

Is the file local or on a share? - Local
Are you able to delete/change/rename the file manually? - Yes
If loacal, check with Process Explorer or handle.exe - No matching handles found.

Are you able to issue the Clear-Content manually?
If so, the script's autorization has to be the issue.

Are you able to issue the Clear-Content manually? - Nope same result

Then the following shouldn't work either:

"" > C:\logfile
Clear-Content c:\logfile -force

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with the proper path and filename, of course.

What does this do

"" > C:\logfile

Overwrite your log file with an empty string - (almost) the same as Clear-Content should do.

Access to Path is denied
UnauthorizedAccessException

Thanks for the points, but I can't see a solution here?

Don't know what it was.  Deleted file, let it get recreated and bingo it worked.

No restart in between, no changes to security .. it just started working