A SharePoint site does not allow a file type that needs to be uploaded (.dwg, .swf, etc.).

1. Ensure that the file extension is mapped in IIS (MIME type). If not, add the MIME type using values obtained from the list at the following site:
http://www.webmaster-toolkit.com/mime-types.shtml

2. Ensure the file type is not a “blocked file type” in SharePoint by:
a. Go into SharePoint Central Admin
b. Click on "Manage Blocked File Types"
c. Remove the file type from the list.

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