When you try to save Microsoft Word 2011 for Mac or Powerpoint 2011 for Mac document you may receive the following error message:
This is not a valid file name. Try one or more of the following: Check the path to make sure it was typed correctly. Select a file from the list of files and folders.
In addition, when opening a file, you may receive the following error message:
"<Application> Cannot open this file. The file might be in use, the file might not be a valid, <application> file, or the filename might contain invalid characters."
This issue can occur, if you are trying to save a file with an invalid character in the file name. Some characters have special purposes and aren't valid within file names.
Examples of these characters are: < (less-than sign)
> (greater-than sign)
/ (forward slash)
\ (backward slash)
If you have tried to use an unusual character in the file name (as listed in the Cause section of this article), remove it from the file name and then try saving the file.
If the file you are trying to open has an invalid character, rename the file and then try to open it again.