I can't upload file to my downloads section

Whenever I try to upload an zip file with the size of 5.6MB to downloads section, Bitbucket shows the 500 Internal Server Error page and fails. As 500 page says that "We've been notified", I think the error log must have been sent to you.

The strange thing is that I can upload the other file with the size of 7.5KB without any problem.

Would this be a temporal problem or a bug should be fixed?

Thanks in advance.