WebM won't upload to X (Twitter)? What to check
WebM is not listed for X Media Studio uploads. Check the upload surface first, then the actual codec, duration and file size. This compatibility record does not diagnose your particular file.
Check these first
- Media Studio only; not a specification for native app, web or API uploads
- Read the exact upload or processing error
- Check file size and duration against the scoped requirements
- Inspect the actual codec in an editor; extension and MIME are only labels
- Compare playback of the original with the exported copy
Likely causes
- Upload surface or format requirements differ
Identify the app, browser or API used for the failed attempt. This reference covers: Media Studio only; not a specification for native app, web or API uploads.
- The export itself is incomplete or corrupted
An interrupted export, a killed app, or a file copied while still writing can look fine in a file browser but fail to open or upload anywhere. Re-export from the original source rather than re-trying the same file.
Fix it
- Re-export from the original source
Rather than repairing a suspect file, export a fresh copy from the camera roll or editor and try that instead.
- Convert it to MP4
This browser converter accepts files up to 100 MB, re-encodes them and can lose quality. Convert a copy from the original and preview the generated video and audio before uploading it yourself.
Convert to MP4
Check your file
Extension and MIME type are labels, not proof of the container. Dimensions and duration come from this browser's media reader. This does not detect codecs, bitrate, corruption or platform upload compatibility. Files and measurements are not sent anywhere.
Platform reference and evidence
These reference values have partial source coverage. Ratios and dimensions are editing guidance; account and upload-surface limits can differ. Approximate or unknown values do not certify eligibility.
- Platform
- X (Twitter)
- Editing ratio
- 16:9 or 1:1
- Max length
- up to 2 minutes 20 seconds for most accounts
- Max file size
- ~512 MB
- WebM support
- No
Duration and size: reference and limitations. Approximate values still need confirmation in your composer.
Format reference scope: Media Studio only; not a specification for native app, web or API uploads. Source checked 2026-09-12; this does not verify every reference field. X Media Studio Library
Full X (Twitter) spec cheat sheet · Does X (Twitter) support WebM?
Prepare a copy in Koldflux, review its output and check the current destination requirements before publishing.
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