Error Processing File

Hi,

I just downloaded the ShortPixel plugin to compress the images across my site, and I got this error message for some of the photos:

Error processing file: There was an error and your request was not processed. (Invalid image or unsupported image format.)

This seems strange to me, because the photos are in the same format as the other images that were processed. How do I fix this error so that I can finish compression?

Thanks!

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