Direct answer

Two values sources define the same key with incompatible types. Keep the key consistently shaped across chart defaults and override files.

Where this error appears

Helm values coalescing

Root cause

The chart may define a key as a mapping while an environment file or --set flag replaces it with a string, boolean, or list.

Minimal reproduction

# chart values.yaml
service:
  port: 8080

# override.yaml
service: disabled

Corrected example

# override.yaml
service:
  enabled: false
  port: 8080

Verify the fix

helm template demo ./chart -f override.yaml --debug

Things to check

  • Compare the key in every -f file.
  • Remember that later values files have higher precedence.

Authoritative reference

Confirm version-specific behavior in Helm values files。