Why was my file rejected?
Check a file against where it is going, and fix every violation at once.
Platforms rarely tell you which rule you broke. They say the upload failed. This checks a file against every published rule for where it is going, lists exactly which ones it fails, and then produces a file that passes all of them at once.
Specs it knows
- WhatsApp sticker: WEBP, 512 by 512, under 100KB.
- Telegram sticker: PNG or WEBP, 512px on the long side.
- Discord custom emoji: under 256KB.
- Instagram feed, story and reel dimensions.
- YouTube thumbnail: 1280 by 720, under 2MB.
- Open Graph share card: 1200 by 630.
- Gmail and Outlook attachment ceilings.
What a failed check looks like
- Wrong format, which no amount of renaming fixes.
- Wrong aspect ratio, cropped or padded to fit.
- Over the byte ceiling, solved by searching for a fitting quality.
- Wrong dimensions, resized to the exact numbers required.
Why a file that passes can still be refused
- Platforms enforce limits beyond the ones they publish.
- Video codecs and audio channel counts are the usual unpublished culprits.
- Converting to plain MP4 with H.264 video and AAC audio clears almost all of them.
Why the limits keep changing
- Every platform revises its caps, and rarely announces it.
- A file that uploaded fine last year can be refused today with no explanation.
- The check is against current published requirements, not remembered ones.
Questions
Why does WhatsApp reject my sticker?
Almost always format or size. A sticker must be WEBP, exactly 512 by 512, and under 100KB. A PNG that looks right still fails on all three counts.
What size should an Instagram reel cover be?
1080 by 1920, a 9:16 portrait frame. Anything else is cropped by Instagram, usually not where you would have cropped it.
Can it fix every problem at once?
Yes. The fix applies format, dimensions and size together, so the output passes every rule in the spec rather than one at a time.