Outook Error: The function cannot be performed because the message has been changed.

The function cannot be performed because the message has been changed.

I’ve been getting this error message with Outlook 2016 and my cloud email. Here’s the quick fix if you run into it too.

Click on File, Options, Mail. Scroll down to Conversation Clean Up. Uncheck When a reply modifies a message, don’t move the original.

Let me know if this works for you!



  1. I was excited to see you had a fix. I tried it AND IT DID NOT WORK FOR ME. My problem is a little different. I use flags in emails to identify when an electronic bill is due. When I pay the bill, I used to be able to click the flag again and it would change to a green check mark. Then I switched to Outlook 2016 and I always get the error “The operation cannot be performed because the message has changed.”

  2. This problem disappeared for me and I thought the last few patches would have fixed the problem. I think the common problem seems to be that people have multiple clients accessing the same account. If you can, try to check email from one client/device. If you can’t, other’s have suggested to disable the auto save function.

    Turn automatic saving of draft messages on or off or change how often drafts are saved
    1. Select File > Options..
    2. In the left pane, click Mail.
    3. Under Save messages, select or clear the Automatically save items that have not been sent after this many minutes check box.

    You can also use this option to change how often draft messages are saved. Enter any value between 1 and 99.

  3. This is all well and good if you are responding to an email. I get this error when trying to attach a .pdf to a new email message. No changing being done. Brand new.

  4. Hi Paula,
    Yes, I’m seeing a lot of these kinds of errors with the new Outlook. By chance, do you have multiple machines/devices checking email at the same time?

  5. Cached Exchange Mode fixed my issue as well. It was disabled and re-enabling it fixed the issue with PDFs that could not be forwarded.

  6. Had the problem that I could not clear flags and got this error instead (Outlook 365 / 2019). Your suggestion to look up “conversation clean up” got me on the right way to solve the issue (-> uncheck “don’t remove flagged messages”).


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