The other day I was trying to upload a file with a particularly hostile file extension into a SharePoint document library. When uploading it through Windows Explorer I would get an error like:
When I tried to upload the same file through the browser UI I got a slightly better error:
SharePoint manages a list of file types per web application that are not allowed to be uploaded or downloaded. It also affects their behavior on server. For example if you were unpacking a .ZIP in a document library files that had blocked extensions would not be unzipped. A possible solution is to remove this file extension as a blocked type. To do this:
- Open up the SharePoint Central Administration web site.
- Under Operations click on Blocked File Types under the Security Configuration section.
- Select the Web Application that you want to allow/block the file type for and add/remove the extension from the list.
- Click OK. When you revisit your document library you should be able to upload those types of files.
That's it. Hope that helps someone.