WARNING: Be extremely careful not to install the latest firmware after following this tutorial! Also make sure to NOT delete other files and folders on your PS4 via FTP!!!!

I'm writing this tutorial for those of you who have decided to update from firmware 4.05 to 4.55 and can't because of an error. This error is caused by either manually creating the required update folders via FTP, running the upload blocker payload or running HEN. I have not yet updated to firmware 4.55, and I suggest you consider the advantages and disadvantages before installing a higher firmware on your console.

I'll start of by saying either way the update blocker is installed on your system, it created two empty folders on your PS4 system. When we delete these folders via FTP you should be able to update again via USB. If possible make sure your PS4 is not connected to the internet while following this tutorial or disconnect your PS4 as soon as the update blocker folders are deleted! I don't want Sony to push the latest firmware update on your console!

Do this the way you prefer.
When using Exploit Host by Al-Azif I recommend 'xVortex + FTP'
When using any online method I recommend 'xVortex + FTP'
If you are using an exploit without implemented FTP payload, inject a FTP payload which grants you full permissions

Open the FTP Software (Host = PS4 IP / Username = "Blank" / Password = "Blank" / Port = 1337) and press connect.
Navigate to /update
You'll find two empty folders 'PS4UPDATE.PUP' and 'PS4UPDATE.PUP.temp.net'
Delete these!