Invalid Filename Characters

An issue came up where an individual attempted to upload a file with the number sign (#) in the filename. Although the Windows file system does not have an issue with this character in a filename, SharePoint does. Although I am sure there is a valid reason, the reality is that there is not much we can do to change the restriction.

With this particular incident, I began to wonder what other characters would be invalid in SharePoint filenames. Fortunately, Microsoft has a page that displays the restrictions for filenames, folder names, site names, et cetera located at:

http://support.microsoft.com/default.aspx?scid=kb;en-us;905231

For my concerns specifically, the following is extracted from Microsoft’s page is:

File name restrictions:

• You cannot use the following characters anywhere in a file name:
  • tilde (~)
  • number sign (#)
  • percent (%)
  • ampersand (&)
  • asterisk (*)
  • braces ({ })
  • backslash (\)
  • colon (:)
  • angle brackets (< >)
  • question mark (?)
  • slash (/)
  • pipe ()
  • quotation mark (“)
• You cannot use the period character consecutively in the middle of a file name.
• You cannot use the period character at the end of a file name.
• You cannot start a file name with the period character.