An error occurred while saving the commentJohn Nash commented
Yes, I ran into this problem as well. Many files in our environment have an underscore character ("_") in the filename.
Interestingly, the Microsoft Support article that talks about invalid characters does not even mention or list the underscore character as being among the invalid / disallowed ones. So the question is, where is this unnamed / unlisted restriction for barring the use of the underscore character coming from?
Microsoft: Please remove this restriction ASAP, thanks!