I do not have the exact folder that update had a problem with.
However, with the last two (now) updates the same issue has been happening. I just tried deleting the plugin and then going through the WoordPress.org install via my dashboard to add the plugin again and I get the following (which is exactly the same issue as with attempting to update)
Could not copy file. image-pro-wordpress-image-media-management-and-resizing-done-right/src/thumb/docs/phpthumb.changelog.txt
When I brought this up you had the update to .29 now it is .30 and it is exactly the same issue.
I fail to see where my server would be having issues with a fresh install of your plugin. I have no issues with any other plugin updating or installing.
The issue was resolved with the previous update prior to .29 where it referred to something to do with tinymce by me using ftp. However, the point is, why am I having to use ftp on your plugin and not others. I can download and upload plugins without having issues. That’s fine, but why is there an issue with your plugin using the WordPress update and not other plugins?
And I cannot even install your plugin without using ftp because trying to copy the file phpthumb.changelog.txt stops the update and the fresh install. Could it possibly have to do with the multiple dots in the name rather than using dashes? I don’t know.