[Windows 10 Mobile] sigfrid696:
For those who are still waiting for a fix for the update error and don't want to undergo the recovery process, I found a different solution, which doesn't need a recovery operation on the phone.

I tested it on my 1020 and another 925 which were stuck in the CU build .297 with success.

Keep in mind that the parameters that I will use are specific to these phone models and if you have a different model you need to find the requested parameters specific to your phone model.

This is an heuristic procedure, tested on a limited number of phones, so use it at your risk, keeping in mind that you could have problems or need to recover your phone loosing all your data, so do before a proper backup.

Let's start.

The problem appears because during update phase the oeminput.xml file becomes corrupted: as far as I know it happens only for some x20 model, and not for all the users.

Now we're going to rebuild it...

Go to the following link

https://msdn.microsoft.com/en-us/library/windows/hardware/dn756630(v=vs.85).aspx

Copy the content of example file oeminput.xml: i.e. copy the content of the framed zone after the phrase "The following example shows the contents of a sample ProductionOEMInput.xml file"

Paste in a .txt file which you'll rename and change extension so that it is oeminput.xml. Save it with notepad.

Now modify the file

<SOC>{PROCESSOR_NAME}</SOC>

at the node <SOC>{PROCESSOR_NAME}</SOC> modify {PROCESSOR_NAME} fake parameter in order to have the processor name of your phone: for the 920/925/1020 use QC8960

at the node <Resolution>480x800</Resolution> instead of 480x800 use the resolution of your phone: for the 920/925/1020 use 768x1280

in all the nodes related to language <Language>en-US</Language> use the language of your phone: I used for example it-IT because I have the phone in Italian language.

Save the file.

Now if you still don't have interop tools installed (but I think you should have if you arrived to CU with an x20 phone model) install it.

Launch interop tools and then click this device and enable full file system access. Reboot your phone, connect it to a pc with cable: you'll see more directories than usual, because you unlocked also system dirs: be careful not to delete or modify any dir apart from what you find in this guide or you'll risk to damage your phone. If you want to find your usual dirs (docs photos...etc), go to phone\Data\Users\Public. I advise you that after the procedure I couldn't deactivate full file system access, because it continues re-activating in interop tools, maybe there is a way: but you can live with this, because you can find the usual dirs in the path that I specified...

Now go to phone\windows\imageupdate, make a backup on pc of the current oeminput.xml and overwrite it with the new one.

At this point in the phone go to settings, update and then search for updates: you should find Fall Creators Update...

Let me know if you have problems or need more informations...

Good Luck!

p.s. I didn't extensively search on the forum if a similar guide has been already posted, in the case sorry for the duplication.

Thanks to Antonio who has actively participated in the realization of this guide