Persistent "Ignoring bad library name" notification

Every time I start Arduino IDE, a notification appears:

“Ignoring bad library name” The library “AVR Standard_C_(C90)_Time_Library” cannot be used. Library names must contain only basic letters and numbers etc.

I reinstalled the program but this message still shows up every time I start Arduino or open library manager. How to get rid of it?

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There's a folder in one of your library folders named AVR Standard_C_(C90)_Time_Library. The most probable location is {sketchbook folder}/libraries. You can find the location of the sketchbook folder at File > Preferences > Sketchbook location. This is not a valid library folder name, please rename the folder to AVR_Standard_C_C90_Time_Library. That will solve the issue.

Thanks, this solved the problem.

pert:
There's a folder in one of your library folders named AVR Standard_C_(C90)_Time_Library. The most probable location is {sketchbook folder}/libraries. You can find the location of the sketchbook folder at File > Preferences > Sketchbook location. This is not a valid library folder name, please rename the folder to AVR_Standard_C_C90_Time_Library. That will solve the issue.

I have the same problem, but with the message the library "New folder" cannot be used. I also can t find sketchbook file preferences and sketchbook location.

Ok, my problem was that i wasn’t searching in the right place. It’s not where thearduino.exe is located. Instead, the libraries that was mentioned earlier are located in documents, as in the picture.

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