Trying to export an EC2 instance fails with the error:

Access denied to the bucket <bucket>
ErrorCode: InvalidParameter

Reason:
AWS has no access to write to the bucket

Fix:
Add the correct ACL to the bucket. You can find the ACLs here: Exporting an instance as a VM using VM Import/Export -> Prerequisites

You most likely need “All other Regions”

All other Regions:
c4d8eabf8db69dbe46bfe0e517100c554f01200b104d59cd408e777ba442a322