I followed the instructions on the support pages to transfer my profiles from an old '''W7''' laptop to a new '''W10''' one. After the copying of the profiles to the correct locations neither Firefox nor Thunderbird would start complaining that they could not find the profiles. What I did (same thing for Thunderbird) 1. Opened Firefox troubleshooting on the old W7 laptop, opened the profile folder. 2. Closed Firefox 3. moved two levels up 4. copied the Profiles folder to a usb drive. On new W 10 laptop 1. Opened Firefox troubleshooting on new W10 laptop, opened the profile folder. 2. Closed Firefox 3. moved two levels up 4. renamed the existing Profiles folder to Profiles OLD 5. copied the Profiles folder from the usb to the same correct location on the new laptop When I tried opening Firefox on the new laptop it would not open complaining that it could not find the profile. Firefox had opened correctly previously. Then when I renamed the moved Profiles folder to Profiles NEW and renamed Profiles OLD to Profiles, Firefox opened normally on the new laptop. Identical procedure and result with the Thunderbird profile transfer. What should I do? Thanks.