Plugin causing HTTP error with pdf uploads

Hi!

Firstly, thx for the plugin, it is working almost great so far!

But if the plugin is activated, I cannot upload pdf files to my site anymore. When trying, the uploader spins and spins and breaks with an http error (just this error message). The problem is this is causing my site also to be not reachable for a while, I assume the process is still hanging there thus preventing the request.

I am using Easy Digital Downloads and when I deactivate the Revive Old Posts plugin, the upload is working without problems… 🙁

https://ww.wp.xz.cn/plugins/tweet-old-post/