Mapping Values Are Not Allowed Here – YAML Error Fix

Local only

A colon followed by a space has structural meaning in YAML. An unquoted command or text value containing that sequence can be mistaken for another mapping entry.

38 chars · 2 lines

Waiting for input

Loading YAML parser…

YAML colon troubleshooting

How to fix mapping values are not allowed here in YAML

The validator sample contains status: ready inside an unquoted command value. Because colon-space marks a mapping value in block YAML, the parser cannot treat the whole line as the intended plain string. This tool is free to use. No account or payment is required.

Last updated

What you can do here

  • YAML 1.2 parser validation
  • Duplicate mapping key detection
  • Preloaded broken YAML example
  • Readable parser feedback
  • .yaml and .yml file import
  • Browser-local processing

Steps

  1. Locate the colon near the parser error and decide whether it is structure or text.
  2. Quote the complete value when colon-space belongs inside a string.
  3. Validate again and confirm the corrected value still contains the intended text.

Colon-space has special meaning in YAML

The sequence ': ' separates a mapping key from its value. Plain scalars that contain the same sequence can therefore become ambiguous unless they are quoted or represented as block text.

Check indentation before adding quotes everywhere

The same broad parser message can also follow a malformed block. Inspect the surrounding indentation first so quoting does not hide a structural mistake elsewhere in the mapping.

Colon inside a command value

Quote the full command so status: ready is treated as string data.

Invalid YAML

service:
  command: echo status: ready

Corrected YAML

service:
  command: "echo status: ready"

Common questions

Frequently asked questions

Why does a colon cause a YAML mapping error?

A colon followed by whitespace separates mapping keys and values, so that character sequence is structural unless the surrounding scalar makes its intent unambiguous.

Should every YAML value containing a colon be quoted?

Not every colon requires quoting, but quoting is a clear fix when colon-space is intended as literal string content.

Can indentation also cause this error?

Yes. A malformed block can put a mapping separator in a context where another mapping value is not legal, so inspect surrounding indentation as well.

Recommended next steps

Could Not Find Expected ':' in YAMLFind a malformed mapping entry where a key/value separator is missing.YAML Indentation ErrorFind mapping or sequence lines that are indented at the wrong nesting level.YAML Validator Online – Check YAML SyntaxPaste any YAML document and inspect parser feedback locally.

Debugging a specific YAML issue? Browse YAML troubleshooting.