My usual trick is to disable s3 uploads before making the move, but I assume you don’t have that choice since your original forum is down.
I am not 100% sure if this would work - you could try this
- set
DISCOURSE_ENABLE_S3_UPLOADS: falsein your app.yml - restore
- remove that line
- rebuild
If it doesn’t work then you could try to edit the dump.sql file in the backup and set the setting to false there.