Kafka Error UNACCEPTABLE_CREDENTIAL
Error code 93 · Non-retriable Security
Requested credential would not meet criteria for acceptability.
Common Causes
- AlterUserScramCredentials request specified an iteration count below Kafka's minimum for SCRAM credentials
- A malformed SCRAM credential payload was submitted (for example missing password material or an invalid mechanism block)
- Credential-management automation generated an invalid SCRAM config string for kafka-configs.sh or AdminClient
Solutions
- Check the iteration count in the SCRAM credential request: Kafka requires at least 4096 iterations for SHA-256 and SHA-512
- Validate the exact SCRAM config string before applying it, for example `SCRAM-SHA-256=[iterations=8192,password=<pwd>]`
- Review broker logs for the specific rejection reason, then correct the credential parameters and resubmit with kafka-configs.sh or AdminClient
Diagnostic Commands
# Check user credential configuration
kafka-configs.sh --bootstrap-server localhost:9092 --describe --entity-type users --entity-name <username>
# Look for credential events in logs
grep 'UnacceptableCredential\|SCRAM\|credential' /var/log/kafka/server.log | tail -20
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