If you didn’t download your historic data per their al too short EOL notice then it’s lost! The Community integration from TTN is now effectively dead and indeed likely generates an error each time it attempts to upload so best go into each application (or device level if set from there) and delete the webhook/ integration to save load on TTN servers…have been doing same myself after long time use (pre-TTN). You will then need to pick and set up a integration from those offered and start again with your choice of dashboard. Many alternates (if not so easy to use by default for us non-softies!) discussed on the Forum (search) over the years.