Upgrade from PSE 2021 - catalog won't convert

Hi, like may people I've been caught by the upgrade to Tahoe of my Mac so that PSE 21 no longer loads. I''m not sure if pressing on with Elements is the right thing for me but I had over 120k photos all carefully tagged, so in the short term I was loading the trial of 2026 to see what that was like. Unfortunately I'm getting an error when I try to convert my catalog. The message tells me to fix the error (no description) in the original software but obviously I can't do that. Has anyone encountered (and solved!) a similar issue?