Breaking YouTube Severity: medium
YouTube captions.insert and captions.update drop the sync parameter after 12 April 2024
What changed
The 13 March 2024 revision history entry says the sync parameter on captions.insert and captions.update was dropped after 12 April 2024. After that date, caption uploads need timing information or they fail. A separate 12 March 2024 entry also limits caption snippet.name to 150 characters, returning a nameTooLong error for longer names.
What it means
Caption uploads without timing information fail instead of being auto synced.
Who is affected
Developers of tools that upload subtitles or caption files to YouTube.
What to do by 12 Apr 2024
Send caption files that already contain timing information. Do not rely on the sync parameter. The cutoff was after 12 April 2024.
Primary sources
Checked against the source 26 Oct 2026
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