I have just saved my profile folder from my computer just before it crashed. When I move the complete content a new profile to a brand new profile on a new computer I get a Danish error meassage about an udefinet entity and FF doesn't start. XML tolkningsfejl: udefineret entitet Adresse: chrome://browser/content/browser.xul Linje 345, kolonne 5: <key id="key_quitApplication" key="&quitApplicationCmd.key;" ----^ I can see that the look of Firefox version on my new computer seems quite different from my old - indicating they are 2 different versions and hence there could be a problem just copying the content. As my old FF was really a beloved fried I would like to have it exactly identical on the new computer. So here are the questions: 1 can I find information on the FF version in the old profile and then install the exact same version on my new PC? 2 if not, can anybody help identifying what causes the errormessage? 3 else I copy important files one by one as described in https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile?redirectlocale=en-US&redirectslug=Recovering+important+data+from+an+old+profile