Serious problem on my site.

Normally when that happens you should get a mail with technical details (an error message); did you get that? If not can you check the PHP errorlog for relevant errors?

frank (ao dev)

I recommend asking at https://www.ads-software.com/support/plugin/autoptimize/#new-post so its developers and support community can help you with this.

the developer is here already, see https://www.ads-software.com/support/topic/serious-problem-on-my-site/#post-17294540 ??