Every once in a while I get this message when trying to view a thread. I am signed in at the time. Usually to a message from a subscribed thread.. 
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I get the same thing on occasion. It usually happens when I click on a notification (red number up top in your pic). Same as you, the notification is for a subscribed thread. I can't figure out a pattern because it doesn't happen all the time. -
Maybe it happens because the post has been deleted before you clicked on it.Comment
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Had the same thing happen a few times... never noticed a missing post. And a new one today. Made a reply post to a thread and got a light green box with "unauthorized post"...???See my completed Magic Pie V5 rear hub motor E-Bike build HERE.Comment
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