Glue Crawler: The number of unique events received is 0 for the target

Question

I've created a crawler that pulls messages from SQS when new objects are added on S3 but when it runs the message "The number of unique events received is 0 for the target" is printed and the expected table isn't created. When I remove S3 events from crawler settings the tables are created successfully.

Execution logs:

BENCHMARK : Running Start Crawl for Crawler [crawler_name]
INFO : The crawl is running by consuming Amazon S3 events.
INFO : The number of messages in the SQS queue arn:aws:sqs:[myqueue] is 17
INFO : The number of messages in the SQS queue arn:aws:sqs:[myqueue-dlq] is 0
INFO : The number of unique events received is 0 for the target s3://[mybucket]/[myfolder]
BENCHMARK : Crawler has finished running and is in state READY

Answer 1

Are you using Amazon S3 event notification, or Amazon S3 bucket notification to sending out notification to Amazon SQS?. I faced the same issue, for me the issue was caused as I used S3 Event notification ( via AWS Event bridge service ) instead of plain old Amazon S3 bucket notification for forwarding S3 notification messages to Amazon SQS. After switching to Amazon S3 bucket notification this issue was resolved. Message format for Amazon S3 bucket notification and Amazon S3 event notification is different and it seems AWS Glue crawler does not process/recognize message received via Amazon S3 event notification. Hope this helps.