kb/java_null_pointer.md

Java NullPointerException

Symptoms

• Stacktrace contains NullPointerException
• Fails during specific code paths or after deploy
• Sometimes triggered by missing config or feature flags

Checks

• Inspect stacktrace frames to find source file and line
• Validate configuration/feature flag defaults are present
• Add guards for optional fields and log offending values
• Review recent code changes around the failing area
• Add unit tests covering null/missing data inputs

Fix

• Add null checks and default values
• Ensure config/flags are loaded before use
• Deploy fix and monitor for recurrence