Why do MPP files come down as read-only from a VSTS Project Portal?
I can’t say why but I do have a few observations, including some workarounds. First, the observations…
1. The Read-Only flag only seems to happen with MPP files. Microsoft Word and Excel both seem to do a good job of not marking the document as Read-Only. As an aside, Word and Excel both warn that I should trust the source whereas Project opens right up as Read-Only.
2. This behavior is the same whether you go through Internet Explorer into the Project Portal or through Team Explorer.
3. Check Out functionality does not seem make a difference. A checked-out MPP file will still open as Read-Only in Microsoft Project.
4. Likewise, the behavior occurs regardless of the version history settings on the document library.
5. This behavior is consistent with other non-VSTS WSS document libraries. That is, the behavior seems to be based on how Windows SharePoint Services and Microsoft Project cooperate; Team System is just an innocent bystander.
So, what can you do about it?
1. Ignore the warning! The easiest work around is to open it as you normally would, make your changes, and save it back out. When you are informed that the file is read-only, answer OK.
You should be prompted with the Save As dialog, select the original file, click Save and then answer Yes to the question about replacing the existing file.
2. Work off-line. That is, download the file to a local file system, edit it as normal using Project, and then save it back to the local file system. When your changes are complete, use the Upload capability of WSS to move the file back into the document library. Believe it or not, you won’t even be prompted about overwriting the existing file. But that is ok… the new version of the MPP file will be written into the document library over (or as a new version to) the old file.
If anyone knows what’s really going on here, please feel free to share. Otherwise, I’ll keep using my workarounds.