Every time I try to upload a large cover image, I get the following message.
No matter what size or type of extension (.jpeg, jpg, png, eg) I use, I get the same message. It even always says that the image I uploaded is 1.05MB specifically. Small covers work fine.
You have to compress your image, here I leave a web page.
I compressed images so much they didn’t even look like images anymore 
I even used covers I found on the forums to try it lol. Nun worked.
I can try to help you jus dm me I can like convert it 
or send it heree
this happens to me too
unfortunately it’s a bug, I had no other option than uploading the cover in bad quality from so much compression 
support tickets won’t help
Hello @VeryCoolAuthor, please let the support team know about this issue by sending them a help ticket 
Another way to size it is to do 966 x 1334 (it’ll fit both large and small cover art size limits and won’t lose quality/aspect ratio when you upload as large or small cover) >>>> a Joseph Evans tip from his cover making tutorial.