Asus ZenBook: Updates fails with error 0x801901f4

[German]Users with notebooks from the Asus ZenBook series (but perhaps also other models) are faced with the problem of not being able to install Windows updates because they fail with the error code 0x801901f4. However, there is a solution to the problem, as a blog reader reported to me.

Update error 0x801901f4 with Asus ZenBook

Blog reader Tecci contacted me by email at the beginning of May 2024, because he had to deal frequently with the issue of "Updates failing on Asus ZenBook notebooks with installation error 0x801901f4". Tecci came across at least two such cases in the Microsoft Answers forum in 2023. Here are two links to these forum posts.

• Having an issue with 0x801901f4 error updating windows
• Windows Update Error: 0x801901f4 & Windows Store Error: 0x80248014

The forum posts don't provide too much information, except that it's probably Asus ZenBooks and people are running into this error during the update installation. The error code 0x801901f4 means:

HTTP_E_STATUS_SERVER_ERROR  – Internal server error (500)

which is not very meaningful. The reader wrote: There are some long-suffering users with Asus ZenBook laptops, but perhaps other models as well, who can't install updates because they fail with error code: 0x801901f4. Because he couldn't get any further in the Microsoft Answers forums, but had the cases on his desk (he works as an IT supporter), he did further research on his own. He came across an explanation and a solution.

Explaining the root cause

What struck him was the fact that the error strangely (and known) only occurs on Asus ZenBook laptops. The reader then asked himself why Asus ZenBooks in particular were causing problems, and this led him to discover why the error was occurring.

The Windows update client sends to the server HTTPS://slscr.update.microsoft.com/SLS/, packed in a URL, among other things the system manufacturer of the computer, the model name of the system, the operating system build etc.

This looks like this, for example (here an Asus ZenBook UX393EA is being updated):

HTTPS://slscr.update.microsoft.com/SLS/{9482F6B4-E363-43B6-B270-9A65BC822D77}/x64/10.0.22621.525/0?CH=234&L=en-US&P=&PT=0x30&WUA=922.728.511.0&MK=ASUSTeK+COMPUTER+INC.&MD=ZenBook+UX393EA

However, on the computers where the update fails with the above error code, the URL looks like this:

HTTPS://slscr.update.microsoft.com/SLS/{9482F6B4-E363-43B6-B270-9A65BC822D77}/x64/10.0.22621.525/0?CH=234&L=en-US&P=&PT=0x30&WUA=922.728.511.0&MK=ASUSTeK+COMPUTER+INC.&MD=ZenBook+UX393EA_%3C!DOCTYPE

and this causes the error. In the URL, the designation: <!Doctype is appended at the end. The reader asked himself: Where does this !Doctype at the end come from? The answer is: "From the UEFI of the computer."

Asus has apparently programmed an incorrect system model name into the UEFI of various ZenBooks and the special characters and the word doctype interfere with the Windows update routine, causing the update attempts to end with the error. The incorrect model name is displayed with msinfo32, the two images below are from this MS Answers forum thread):

This was discovered by a user who posted the information on reddit.com in the article Changing (Fixing) System Model in ZenBook BIOS/UEFI and also described a workaround there. He has patched the string, but this does not survive a reboot.

ASUS would have to take action here and fix the incorrect string in the UEFI model name. Tecci writes that the problem cases known to him have probably affected ASUS Zenbooks from abroad. However, if someone encounters the problem, the cause is described here.