Allow MS Access *.mdb Files for Upload and Download

This will take a surprising number of steps to accomplish. With SharePoint on top of IIS 7, Access files (MDB) get blocked at all three layers of the service stack: IIS, ASP.NET, and SharePoint.  So simply removing them from the blocked file list in the SharePoint Central Administrator isn’t enough — both IIS and ASP.NET still have mechanisms that get in the way.

Step 1) Sharepoint MDB Blocking

There is a list of blocked filetypes in Sharepoint Central Administration –> Operations –> Security Configuration –> Blocked file types. Find *.mdb and delete from list. When you do this an entry will be automatically created in the Sharepoint site’s web.config file,

<system.webServer>
   ….
   <security>
     <requestFiltering>
       …
       <verbs>
         …
       </verbs>
       <fileExtensions>
             <remove fileExtension=".mdb" />
       </fileExtensions>
     </requestFiltering>
   </security>
  ……
</system.webServer>

{Step 2 & 3 after jump}

Step 2) IIS MDB Blocking

To stop IIS from blocking MDB files, logon to the WFE server(s) and launch the IIS Manager MMC snap-in and browse to the site that’s mapped to the SharePoint web application.  Under the "Request Filtering" icon and the File Name Extensions tab look for the ".mdb" extension as not allowed.  Select this entry and click "X Remove…".  

Step 3 ASP.NET MDB Blocking/Treating MDB as Script File

Back in IIS Manager at your WFE site open up the Handler Mappings. Look under the Path column for “*.mdb”. You may see a couple of entries which I don’t know the legacy here of why asp.net wants to treat *.mdb as script file extentions but it does. Don’t make any changes here though…these are added by a default configuration for for asp.net and also Sharepoint’s web.config file. 

Override this behavior by making a new entry in the Sharepoint WFE’s web.config file (don’t mess with the existing entry that adds a mapping). You’ll find this file at the wwwroot of your WFE (Drive:\inetpub\wwwroot\wss\VirtualDirectories\80) Open with Notepad and locate the <httpHandlers> section and add:

<httpHandlers>
      <remove verb="*" path="*.mdb" />
      …….
</httpHandlers>

After taking those three steps — unblocking MDB files in SharePoint, IIS, and ASP.NET – you’ll be able to upload and download MS Access files from your Sharepoint document libraries.

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