Timeout and Connection Errors
There appears to be a bug related to cookies/sessions and the new "Unread posts" functions.
After long or many forum sessions I and another Admin have experienced connection timeouts or "ERR_SPDY_PROTOCOL_ERROR" on topic links which is I think, is a false positive. If we logout from the forum those same links are then delivered with no error, login again then same error is thrown. After some troubleshooting we found that if we click the "Mark all read" link while logged in the error goes away.
This issue is already fixed. Please wait for the next update.
You just need to click on "Mark all read" link each time when this issue happens.
There is no any ETA yet. We don't have any urgent issues so it'll released when we finished all planned changes in core.
I'm sorry, but you need to wait for the next update.