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Arquivado

A newer version of Thunderbird may have made changes to your profile which are no longer compatible with this older version.

Wayne Mery replied
JayinOK

A newer version of Thunderbird may have made changes to your profile which are no longer compatible with this older version. Use this profile only with that newer version, or create a new profile for this installation of Thunderbird. Creating a new profile requires setting up your accounts, calendars and add-ons again.

More information…

THIS NEEDS AN OPTION TO CONTINUE USING OLD PROFILE. YOU JUST MADE THUNDERBIRD USELESS TO ME. DO NOT KNOW HOW TO CREARE A NEW PROFILE. SHOULD NOT NEED TO. CAN NOT START IT AFTER MANY YEARS OF USE. PREFERRED OLD VERSION OF ABOUT 5 YEARS AGO. JAY

A newer version of Thunderbird may have made changes to your profile which are no longer compatible with this older version. Use this profile only with that newer version, or create a new profile for this installation of Thunderbird. Creating a new profile requires setting up your accounts, calendars and add-ons again. More information… THIS NEEDS AN OPTION TO CONTINUE USING OLD PROFILE. YOU JUST MADE THUNDERBIRD USELESS TO ME. DO NOT KNOW HOW TO CREARE A NEW PROFILE. SHOULD NOT NEED TO. CAN NOT START IT AFTER MANY YEARS OF USE. PREFERRED OLD VERSION OF ABOUT 5 YEARS AGO. JAY

Wayne Mery modificouno o

All Replies (2)

Open a Run window (Windowskey+R), enter

thunderbird.exe --allow-downgrade -p

select the old profile.

Jay, your old profile is probably still there. See https://support.mozilla.org/en-US/kb/profiles-where-thunderbird-stores-user-data#w_finding-your-profile-without-opening-thunderbird for a description of how to find the directory names.

In Windows' list of installed programs, what version(s) of Thunderbird are shown as installed?