Trying to migrate Firefox profile from Win 7 machine to new Win 10. Downloaded Firefox to new machine, confirmed that it worked, closed it.Using Troubleshooting feature, located active profile in old Win 7 machine, copied to USB stick. Closed Firefox on new machine, navigated to Profiles folder, copied the Win 7 file to it and deleted the existing file. Tried to start Firefox, got 'Your Firefox profile cannot be loaded. It may be missing or inaccessible'. Fiddled round a bit, finally uninstalled Firefox from the new machine and downloaded it again. Got the same error message, now no Firefox at all after carefully following such instructions as I could find. What the f*ck am I doing wrong? A year or so ago I transferred the Win 7 profile successfully to a Win 10 laptop. What has gone wrong now? Any suggestions most welcome.