You are migrating a large set of files from a public HTTPS source to a Cloud Storage bucket for NexaData Corp. Access to the files is secured using signed URLs, and you’ve prepared a TSV file listing all the URLs. You initiated the migration using Storage Transfer Service (STS). The transfer ran successfully for a while but then failed, and job logs show HTTP 403 errors for the remaining files. You verified that nothing changed on the source system. You now need to resolve the issue and resume the migration. What should you do?