Media Library Upload Error

Hello,
I was able to upload images to my media library without any issue just a couple weeks ago.
Currently I am experiencing the following error when trying to upload an image;
“An error occurred in the upload. Please try again later.”
The permissions on the upload folder is set to 755. When I switch the theme to a default WP theme, I am able to upload an image without out issue. Any insight on this would be greatly appreciated.

Tommy

Try using the media uploader in WordPress directly. That is powered by WordPress and has nothing to do with the theme.

The issue I’ve found in not being able to upload from the post page at random times is due to the WP system doing a “draft save” and the system can’t do a draft save AND a media upload from post at same time.

Might not be related, but that was the bizarre thing that happened to me; and happens regardless of theme used, since WP 3.9.

Thank you Christopher for your reply. Yes, I am using the media uploader directly. I open media tab, click on the add new tab and select a file on my machine. The thumb nail graphic displays the uploading blue status bar. A couple minutes pass by, error message pops up. The default thumbnail graphic is is a blank file with the name of the file I attempted to upload. I am using WP 4.0. As I stated previously, I do not have an issue doing the same task when I switch to a default WP theme.

Thank you Lucian for your reply. Yes, I did what you suggested before contacting you. My apologizes for not stating that in the beginning. All plugins deactivated, cleared all sites cache and error continues to exist.
As I mentioned to Christopher, when I switch the theme to a default WP theme, I am able to upload using the media uploader directly without any problems. I am using WP 4.0

Regenerating the thumbnails did the trick.
Thank you for your help.

Tommy