failed to open stream: no wrapper found in class-fastimage.php

Hi,

Thanks for this plugin. When using it with my web site, though, it throws a number of errors on regular blog posts with images:

failed to open stream: no suitable wrapper could be found in [...] class-fastimage.php

Any idea why this problem occurs?
And what I can do about it?

Thanks!

– Robert

https://ww.wp.xz.cn/plugins/amp/