YAML "mapping values are not allowed in this context" in CI

The YAML parser hit a : (colon plus space) in a position where a mapping cannot start, usually because a scalar value contains an unquoted colon. It reports "mapping values are not allowed in this context" at that column.

What this error means

Any YAML consumer (kubectl, a schema validator, a CI config loader) fails with "mapping values are not allowed in this context" and a line:column pointing at a colon inside a value.

YAML

error converting YAML to JSON: yaml: line 6: mapping values are not allowed in this context

Common causes

An unquoted colon inside a scalar value

A value like message: build failed: retry has a second : the parser reads as a nested key, which is illegal here.

A misaligned key that lands mid-value

A key indented into the middle of a previous value creates a colon where the parser expected plain text.

How to fix it

Quote values that contain a colon

Go to the reported line and find the second : in the value.
Wrap the whole value in single or double quotes.
Re-parse the file to confirm the error clears.

config.yaml

# wrong
message: build failed: retrying now
# right
message: "build failed: retrying now"

Fix the indentation of a stray key

If a key drifted into a value, re-indent it to the correct level so it is a sibling, not embedded text.

How to prevent it

Always quote scalars that contain : (colon space).
Lint YAML with yamllint before it reaches CI.
Use block scalars for multi-line messages that include colons.