If you're using plugins such as File System or LightSVN, there is a problem when viewing the file content via the "Review Content" tab. This problem also happens when uploading patch file via the "Patches" or "Uploads" tab.

Steps to reproduce;

1. Create a new review
2. Select the file via the "Files" tab (in this case, repository either in File System or LightSVN plugin)
3. Click on "Review Content" tab to view the file
4. You should be able to see the attached error