Blocking Attachment Extensions in Dynamics 365 CRM

You might not want to have certain attachments in Dynamics 365 CRM as it doesn’t make sense for those file types to be considered as attachments. For example – Video Files, Zip Files in case you are skeptical as to what they might contain.

Hence, to counter that – here’s how you can block specific attachments extensions from being used in Dynamics 365 CRM environment.

Blocked Attachment Extensions

Navigate to Power Platform Admin Center ( and then follow the steps below –

  1. In Power Platform Admin Center, select the environment which you want to review what attachment extensions are to be blocked and then click on Settings

  2. Then, expand Product section and go to Privacy + Settings.

  3. Here, you’ll find the Blocked Attachments section which lists all the file extensions that are blocked in Dynamics 365 CRM environment which you have chosen.

  4. Notice that each attachment is separated by a semicolon and the last one doesn’t end with a semicolon.
    To keep the example simple, I’ve entered pdf and we’ll see what error is thrown when the PDF attachment is entered in Notes in CRM.

  5. You can save your changes upon making sure the desired attachments are blocked.

Error for blocked attachments extensions

Now, when you try to attachment files with the blocked extensions, see what happens –

  1. Let’s say as per the above example, we are blocking the PDF extension type.
    Then, let’s try to attach a file to the Sample Note in the Account record.

  2. And I select a PDF file –

  3. And when I try to save the Note, the below error pops up prohibiting me from entering the attachment file which the blocked extension.

    The error will say – “The attachment is either not a valid type or is too large. It cannot be uploaded or downloaded.
  4. However, as the above error suggests, I tried to download the attachment after I unblocked -> uploaded -> blocked the attachment, I was still able to download the PDF file through the browser’s inbuilt functionality.

Hope this was useful!

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Thank you!