I was using Opera v26 to test an alternate account with my main logged into Chrome. I could not get either resources or the images for the post to upload properly. Had no issues uploading an attachment to a thread. Tried it again with all add-ons disabled. It would go into an ajax progress and never end. Saving the resource and looking at it again revealed the files to all have actually uploaded. The following is what the console output: Multiple 'X-Frame-Options' headers with conflicting values ('SAMEORIGIN, DENY') encountered when loading 'https://www.raindd.com/attachments/do-upload'. Falling back to 'DENY'. about:blank:1 Refused to display 'https://www.raindd.com/attachments/do-upload' in a frame because it set 'X-Frame-Options' to 'SAMEORIGIN, DENY'. jquery-1.11.0.min.js:2 Uncaught SecurityError: Failed to read the 'contentDocument' property from 'HTMLIFrameElement': Sandbox access violation: Blocked a frame at "https://www.raindd.com" from accessing a frame at "null". The frame being accessed is sandboxed and lacks the "allow-same-origin" flag. Wasn't having the issue in Chrome. Fresh install of Opera 26. Board URL is set correct. Server forcing all traffic to www and https.