"This file will be changed when it publishes"
What it means: We checked the file when you uploaded it and something about it does not match what the platform accepts, so it will be adjusted on the way out.
The two common ones:
- A video will be re-encoded for Instagram. Instagram only takes 8-bit H.264 up to 1080p, 23–60fps, under 22 Mbps. Anything else — HEVC from an iPhone, 10-bit from CapCut or Resolve, a very high bitrate — we convert first. The note tells you which of those applies. To keep control of the quality, export in that format yourself.
- A PNG will lose its transparency. Instagram saves images as JPEG, which has no transparent areas — they come out black or white. Flatten the image onto the background you want before uploading.
These notes never stop you posting. They are a prediction of what the platform will do, and you can schedule the file exactly as it is if you are happy with the result.
Supported Formats
| Type | Formats | Max Size |
|---|---|---|
| Images | JPG, PNG, GIF, WebP, HEIC, HEIF, BMP | 15 MB |
| GIFs | GIF | 15 MB |
| Videos | MP4, MOV, M4V, AVI, MKV, WebM, FLV, WMV | 200 MB |
iPhone / HEIC Photos
Photos taken on iPhone in HEIC format are automatically converted to JPG during upload. You don't need to do anything — it happens in the background.
MOV Videos
MOV videos (common from iPhone) are automatically converted to high-quality MP4. This keeps quality high while ensuring compatibility with all platforms.
Video Conversion Happens After the Upload
Videos that are not already in the standard format — MOV files from an iPhone, and some 4K recordings — are converted once the upload finishes. The file appears in your library immediately and the conversion runs in the background, usually within a few seconds.
You can keep working while that happens. The only limit is publishing: if you add a video to a post and publish straight away, we hold the post until conversion finishes rather than sending the unconverted file, so it may go out a minute or two after you clicked. Scheduled posts are unaffected.
If a video cannot be converted, any post using it will fail with a message saying so. Re-upload the video — exporting it as MP4 (H.264) from your editor first is the most reliable fix.
Upload Stuck at "Processing"
- Large videos take time to process — give it a few minutes
- If it's stuck for more than 10 minutes, try uploading again
- Check your internet connection — large files upload in chunks, so interrupted uploads can usually resume
File Too Large
If your file is over the size limit, try compressing it before uploading. For videos, reducing the resolution to 1080p usually brings the file size down significantly.
Slow or Unreliable Connections
Large files are sent in small pieces, one piece at a time. If a piece fails it is retried on its own, so a brief drop in connection does not lose the whole upload.
If uploads are still slow or failing:
- Try a different time of day. Home and office connections are often congested in the evening, when everyone nearby is online. The same file can upload several times faster in the morning.
- Upload one file at a time. Several uploads at once share the same connection, so each one gets a fraction of it.
- Use a wired connection or move closer to the router. Weak Wi-Fi and mobile data are the most common cause of stalled uploads.
- Pause other heavy usage. Video calls, streaming and cloud backups compete with your upload for the same connection.
- Compress large videos first. 1080p is plenty for every platform we post to, and a smaller file spends less time in transit.
Upload speed is limited by your own connection rather than by Autoposter, so a file that takes a long time to upload here will usually take a long time to upload anywhere else too.