This is the exact error the yaml parser throws — no rewording, this is the real message you get. It means two keys that are supposed to be siblings in the same mapping don't start at the same column:
name: Ada role: engineer team: platform # <- indented one extra space, breaks the mapping # All mapping items must start at the same column
team is indented one space further than name and role, so the parser can't tell if it's still part of the same mapping or the start of something nested. YAML has no closing brace to mark the end of a block the way JSON does — indentation is the entire signal, so a single stray space changes what the document means instead of just how it looks.
The usual causes
- Copy-pasting a fragment from one part of a file into a more (or less) deeply nested spot without re-indenting it to match.
- Mixing tabs and spaces — YAML doesn't allow tabs for indentation at all, and an editor that silently converts one to the other can leave a line that looks aligned but isn't, byte for byte.
- An editor with auto-indent adding or removing a space when you didn't expect it, especially right after a line ending in
:.
Fixed version
name: Ada role: engineer team: platform
Finding it fast
Whitespace differences are genuinely hard to spot by eye, especially the one-space kind. Paste the same YAML into the converter here — the error message includes the exact line number the parser choked on (via the parser's own linePos, not a guess), so you don't have to eyeball the whole file searching for a misaligned key. An editor with "show whitespace" or "render tabs" turned on catches the tabs-vs-spaces variant of this before it ever gets this far.