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Troubleshooting

Kafka UI Not Launching or Continuously Loading/Crashing

Symptoms: Kafka UI fails to launch, keeps loading indefinitely, or crashes repeatedly. Common indicators include "Sync Replicas are set to 0" errors or schema registry issues.

Solution: 1. Stop all Docker containers: bash make stop 2. Delete the /data folder located at the root of the docker-compose folder. 3. Restart the docker containers: bash make start This process will clear persistent data and typically resolves initialization issues.

This should fix the issue.

JDBC Connector Not Creating Topics

Symptoms: JDBC connector runs but fails to create expected Kafka topics.

Potential Causes & Solutions: - Incorrect SQL Query: Verify your query syntax and test it directly against your database - Incrementing Mode Configuration: When using "mode": "incrementing", the connector automatically appends:

WHERE "version" > ? ORDER BY "version" ASC

The ? parameter is automatically handled for incremental loading. Ensure your main query is compatible with this appended clause.

Resolution Steps:

  1. Fix any query issues identified

  2. Stop containers: make stop

  3. Delete the /data folder

  4. Restart containers: make start

  5. Allow several minutes for topic creation before attempting to create streams

KSQLDB Alert common error

Symptoms: URLs generated in alerts are not clickable or functional due to special characters.

  • # needs encoding as %23 (URL fragment identifier)
  • Spaces need encoding as %20
  • Other special characters may also require encoding

Solution: Since KSQLDB lacks built-in URL encoding functions, manually chain REPLACE statements for each special character:

-- Example encoding for # and space characters
REPLACE(REPLACE(case_id, '#', '%23'), ' ', '%20')

Add additional REPLACE calls for other special characters your data may contain.