I got the same problem.

So today I was not able to join the server duo to a steam bug.
So had to connect to the server via arma3 itself.
But now I am not able to join there anymore aswell,
As it says Verifying PBO failed addons\ui_f.pho ? What ever that may be.
Were there any changes made to the server resently that could have anything to do with this ?
Or how do I solve this. ( I checked the file location, and ui_f is actually there but says its "updated" today.
Please let me know!
Greats, Chatsel{F3115555}

I had the same problem after todays hotfix to correct the launcher problems, my server is set up to automatically run a server update if there is one available but for some reason it did not update, after updating the server it does not give the "Verifying PBO Failed" message.

So if you have access to the backend of your server try running an update. Hope this helps

We have had more than one user experience this issue. I am gathering data (operating system, etc) to see if there's a pattern. So far the only things in common are Spotrep 00112 and addons/ui_f.pbo.

I've confirmed our server _did_ update, as some users are able to connect with updated clients (including me).

Yeah, I'm having the same issues as well, would love to know a fix