Eureka! I'm updated!
Thanks @Shep914. I did as you suggested in your post https://www.dell.com/community/XPS/XPS-13-9350-Windows-10-Update-stalled-because-of-out-of-date/m-p/...
Using the "detect" link on the Intel site, I went ahead and installed the RST driver from Intel (V 22.214.171.1245), since the Dell RST driver's version was in the bad range and was the version I already had installed. After installing Intel's driver and re-booting, the Dell System update window popped up and I clicked the "check" button and some unrelated ethernet driver update was suggested, which I also did.
Then I restarted the Windows 1903 update, which took about an hour of mysterious processing and then after restarting, it took another 1/2 hour to actually install. Then I had another quick "update and restart". Luckily @davidlpotts, in this post https://www.dell.com/community/XPS/XPS-13-9350-Windows-10-Update-stalled-because-of-out-of-date/m-p/... had mentioned that the update took a very long time, so I wasn't too worried about how long it all was taking. I went out for a bike ride.
Thanks @johnptd for all your detail (https://www.dell.com/community/XPS/XPS-13-9350-Windows-10-Update-stalled-because-of-out-of-date/m-p/...) - I also looked at the Device Manager after installing the new version of the RST driver, and I saw that iaStorA.sys was still there in the system32 folder, as well as iaStorAfs.sys. I didn't do any renaming, just restarted the Windows update and it all seems fine. I see that you have an XPS 9550 (not at 9350), so things are probably slightly different on your system.
@davidlpotts Did you use the Intel detect site to install the RST driver? I did that, didn't rename any files, and was able to get the Windows update to work. The level I got was 126.96.36.1995. I'm wondering if you got the wrong driver for your machine since you got a much higher version 188.8.131.521. That is the highest version, but might not be right for your config.
Try this link to have Intel detect and suggest the right driver:
After installing, reboot and try the Win update again.
I was able to update my XPS 9350 using the Intel utility to select and install the applicable RST driver. Note that it selected the 184.108.40.2065 driver for my 9350 and not the latest. After rebooting the Windows update completed without issue. Although the old driver file remained, it was not necessary to rename any files.
I have been a Dell customer since my first computer purchase in 1996. I am pretty disappointed that they are not supporting their customer base with updated drivers especially for their premium XPS line. Please forward this message to the support organization
Thanks for the updates, but I'm afraid it didn't work out well for me. Having already visited the Intel page suggested by Jesse L, and installed the version of the Intel RST driver there, 220.127.116.111, I seem to have been stuck with the later (and apparently incorrect) versions. After reading of the success people were having with Intel's Driver & Support Assistant, first described here by Shep914, I uninstalled the 17.5.xxx version of the RST driver and ran the Driver & Support Assistant. The version of RST it installed was 17.2.xxx (I forget the exact number). This still didn't allow my Windows 10 to be updated to 1093. I couldn't get the Intel tool to install RST version 18.104.22.1685 (which seems to be the right one for the XPS 13 9350).
The good news is that the Intel Driver & Support Assistant seems to provide a solution (if you use it FIRST!).
As for me, I won't go into the gory details, but after some frustrating attempts to roll back to previous versions, my system wound up getting corrupted so badly, I had to rebuild it from the ground up. Thanks, Dell.
Help! I followed the advice "navigate to C:\Windows\System32\drivers. Locate iaStorA.sys and rename it to iastora.sys_x . Now, go ahead with the 1903 update and it would go through" The Windows 10 update would not install. An on screen box asked to close and restart the pc. The pc will now not open windows. The command prompt says insufficient memory to open. Windows cannot be restored or reset to factory. I'm at a loss as to how to proceed
Welcome to the Dell Community @Jess on the hill
Windows 10 May 2019 Update (build 1903) fails to install due to an out-of-date Intel Rapid Storage Technology driver:
If the W10 update fails after updating the (Intel® RST) driver or if there is no updated driver for your model then you can work through the following steps:
If needed the latest (Intel® RST) driver can be found here:
Intel® Rapid Storage Technology (Intel® RST) User Interface and Driver:
The automatic repair section is a dead end. It's from there that I've tried to reset and even recover via USB, but every avenue is blocked and returns back to Automatic repair section.
The only option I haven't tried is factory reset as I'd lose unsaved files.
I did just that, renamed the driver and then rebooted. Of course my XPS 13 9350 wouldn't start without a HD driver! Under Auto repair->advanced i found a tool named "Startup repair" (or something like that) and that fixed it.
The Intel Driver and Support Assistant found my old driver but failed to install a newer one. So I went to manually install it from Intel page https://downloadcenter.intel.com/download/28966/Intel-Rapid-Storage-Technology-Intel-RST-User-Interf.... I picked the first installer in the list, SetUpRST.exe, and according to Device manager it installed version 22.214.171.1241
Now i'm running uppdated Windows!
Having spent the day trying all auto repair and reset options I took my XPS 13 9350 to a computer repair shop, they worked on it for an hour without success.
They eventually placed a new version of Windows 10 from a USB on a partition and restarted the machine.
My original files are all still available but all applications were lost, so another half day re-installing app's.
It's left a bad taste for Dell who'd offer no support as my warranty was three months expired. I feel this was totally their fault as I had not caused the crash, the Windows 10 update was not something I would have known to avoid and once the update was initialised the machine would not reset or recover.
My time is valuable and to waste it like this is frustrating.