Converting several files at once, and what the error messages mean
2026-10-06
Every converter page accepts more than one file. This guide covers how the queue behaves and what to do when a file fails.
Three ways to add files
- Drag and drop one or many files onto the box.
- Click the box and select files; hold Ctrl or Shift (Cmd on a Mac) to select several.
- Paste. Copy a file, or a screenshot, and press Ctrl+V anywhere on the page. This is the quickest way to turn a screenshot on the clipboard into a JPG or WEBP file.
How the queue works
- Files are converted one at a time, in the order they were added. A failed file does not stop the ones after it.
- Set the target format and quality first. Each file takes the settings that are selected at the moment you add it. Changing the quality afterwards affects only files added later.
- Each result downloads automatically under the original name with the new extension. The download button stays in the list so you can save a file again without converting it twice.
- Your browser may ask for permission. When a page saves several files in a row, Chrome and other browsers show a prompt asking whether to allow multiple downloads. Choose Allow, or the later files will be blocked.
- Results live in the tab. Closing or reloading the page discards them, so save what you need first.
Dragged or pasted files do not all have to be the type named on the page, because each file is identified by its own extension. Dropping PNG, WEBP and BMP images together onto a JPG converter converts all of them. The file picker is stricter: it lists only the source type of the page you are on.
How many files is sensible?
For images, dozens at a time is no problem; each takes a fraction of a second. For audio, a full album is fine. For video, add a few at a time. Each video is loaded into memory whole while it is converted, and a long queue of large videos keeps the tab busy for a long while.
Error messages
| Message | What it means | What to do |
|---|---|---|
| Unknown input format | The file extension is not one the site recognises. The format is read from the extension, not the contents | Check the extension. Files with no extension, and formats such as HEIC, PDF or DOCX, are not supported |
| Source and target are the same format | You added an MP3 to an MP3 converter, for example | Pick a different target format |
| Files over 2 GB are not supported in the browser | The file cannot fit in the memory a tab is allowed | Use a desktop program |
| Conversion failed (ffmpeg exit …) | The engine could not read or write the file | See the list below |
Why a conversion fails
- The file is damaged or incomplete. Try playing it in a media player. If it stops early there, it will fail here.
- The file is copy-protected. Purchased films and some music downloads are encrypted.
- There is nothing to convert. Extracting audio from a video that has no soundtrack fails, because the output would be empty.
- The extension is wrong. A file renamed from one format to another may still convert, since the engine inspects the contents, but a mislabelled file can end up on the wrong path. Rename it to its true extension and try again.
The tab freezes or crashes
A page that goes blank, or a browser message such as "Aw, Snap" or "This page was reloaded because it was using significant memory", means the tab ran out of memory. It happens with large videos, most often on phones.
- Close other tabs and apps, then try again.
- Convert the file on a laptop or desktop.
- For video, trim the clip first so there is less to hold in memory.
It seems stuck at the start
The first video or audio conversion downloads the 32 MB conversion engine, and the status line says so. On a slow connection that takes a while; it is cached afterwards. Images going to PNG, JPG or WEBP do not need the engine at all. Why the site works this way is explained in how in-browser conversion works.
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