Thunderbird failed to send and receive emails after the profile folder was moved

Posted on Sep 24, 2013

Thunderbird could not sending and receiving emails although it kept trying, after my old profile folder was moved to a new location. Error console showed the following message.

Your certificate contains the same serial number as another certificate
issued by the certificate authority. Please get a new certificate containing
a unique serial number. (Error code: sec_error_reused_issuer_and_serial)

For more information, see


Older routers will sometimes improperly regenerate their security certificates instead of keeping the same one for the life of the device. If you have added a permanent security exception for your router, and if this regeneration is done improperly, Firefox will detect the change as a possible attack.


The long term solution is to contact your hardware vendor and see if updates are available for your device which fix this problem.


If you are confident that no attack has occurred, you can work around the problem by deleting your old exception and using temporary exceptions for subsequent visits to the page:

To delete your old exception:

  1. At the top of the Firefox window, click on the Firefox button and then select Options
  2. Select the Advanced panel.
  3. Click on the Encryption tab.
  4. Click View Certificates to open the Certificate Manager window.
  5. In the Certificate Manager window click on the Servers tab.
  6. Find the item that corresponds to the site that generates the error. Note the Certificate Authority (CA) for that server – the CA name appears above the site name.cffcf8a9e5e507cd1fb8eb64de821ad3-1257730614-636-1.png
  7. Click on the server certificate that corresponds to the site that generates the error and press Delete….
  8. Click OK when prompted to delete the exception.
  9. Click on the Authorities tab.
  10. Click on the item that corresponds to the CA that you noted earlier and then press Delete….
  11. Click OK when prompted to delete the exception.
  12. Click OK close the Certificate Manager window.
  13. Click OK to close the Options window .