I compressed my images to WebP and the platform will not accept the upload. What now?

First, be sure why it was refused

The rejection message may name the formats outright, such as 'allowed formats: JPG, PNG', or it may be vague, like 'upload failed'. If it is vague, check the platform's help page for accepted formats and the maximum size. If format is the cause, the problem is neither the quality nor the size of your images; the .webp extension simply is not accepted there.

Why the original and not the WebP copy?

The version made from the original is a little bigger but clearly closer to the real picture. The mean difference is the average gap per color channel on a 0 to 255 scale. Converting from WebP starts from an image that has already lost some detail, then loses more, and brings nothing back.

Step by step

1. Gather the originals from your phone or the photographer's files, not from your folder of compressed copies.
2. Add them to the Image compressor, up to 30 at a time.
3. Choose JPEG as the output format, at quality 80 or whatever suits you.
4. If some images have transparency, set the background color field to the color of the platform's product page, because JPEG cannot store transparency.
5. Download and upload. This time the file names end in .jpg.

If the originals are gone

Sometimes the WebP copy is all that is left. Then converting to JPEG is the only way, so pick a high quality such as 90 to limit the extra loss, and accept that the file may be bigger than the WebP. You can do that in the compressor itself, since it accepts WebP files, or in the Image format converter if you only want to change the format. From now on, keep a folder of originals and make each platform its own copy in the format it accepts.