Seems like I sucsessfully uploaded my avatar from another PC. I had (and I still have, just checked it) this issue with any image, so I don't think it's something image-dependent. Here you are my log: Failed to load resource: net::ERR_BLOCKED_BY_CLIENT <a href="https://www.google-analytics.com/analytics.js" rel="nofollow">https://www.google-analytics.com/analytics.js</a> Failed to load resource: net::ERR_BLOCKED_BY_CLIENT <a href="https://partner.googleadservices.com/gpt/pubads_impl_62.js" rel="nofollow">https://partner.googleadservices.com/gpt/pubads_impl_62.js</a> Failed to load resource: net::ERR_BLOCKED_BY_CLIENT <a href="https://tpc.googlesyndication.com/safeframe/1-0-2/html/container.html" rel="nofollow">https://tpc.googlesyndication.com/safeframe/1-0-2/html/container.html</a> Failed to load resource: net::ERR_BLOCKED_BY_CLIENT prevel.js:737 Uncaught SecurityError: Failed to execute 'addEventListener' on 'EventTarget': Blocked a frame with origin "<a href="https://app.roll20.net" rel="nofollow">https://app.roll20.net</a>" from accessing a frame with origin "null". The frame requesting access has a protocol of "https", the frame being accessed has a protocol of "data". Protocols must match. 4appbrowse.js?1431956300:1 autograv <a href="https://js-agent.newrelic.com/nr-632.min.js" rel="nofollow">https://js-agent.newrelic.com/nr-632.min.js</a> Failed to load resource: net::ERR_BLOCKED_BY_CLIENT 8appbrowse.js?1431956300:1 autograv browse.js?1426168778:3 11949147 browse.js?1426168778:3 Uploading a size: 100x100 browse.js:3 Reader load! browse.js:3 img load! browse.js:3 451 browse.js:3 Uploading a size: 200x200 browse.js:3 Reader load! browse.js:3 img load! browse.js:3 451 browse.js:3 Uploading a size: 512x512 browse.js:3 Reader load! browse.js:3 img load! browse.js:3 451 browse.js:3 Uploading a size: 2048x2048 browse.js:3 Reader load! browse.js:3 img load! browse.js:3 451 browse.js:3 Uploading a size: 10000x10000 browse.js:3 Reader load! browse.js:3 img load! browse.js:3 451