Unable to fix the side by side error, my only option may be to re-install Thunderbird or migrate to Outlook. My question is whether its feasible to re-install Thunderbird and still preserve my old profile and emails. I haven't done any backups of Thunderbird but do still have all my emails on the server. Thanks Lance PS I have tried all the suggested fixes as shown in the following link to the side by side error: https://support.mozilla.org/en-US/questions/1439559#answer-1659630