Update error code 30088-27 Office 2021 what to do to get corrected????

I get it but don't have any idea who to trust as I've seen sites selling "keys" for $17, $29, et al.

I completely understand that one. I got 'caught' in one of those a few years ago. I had purchased an "extremely discounted" key from one of those scam sellers (if I remember correctly, it was for Office 2019). Instead of directing me to download the installer from Microsoft's own website, they provided a link to the download. Years later, when I bought a new laptop (I sold the 'old' laptop, but, in transferring everything, a few problems occurred, and I had to reinstall several programs, including Office), and went to re-install it, it wouldn't activate. When I logged into my MS account, it was not listed. That's what led me to getting Office 2021.

When searching 'discount' sellers, you will typically find two primary types - those who are honest, directing you to log into your MS account, and add the key...and, the rest (who are dishonest). That's the easiest way to differentiate between the 'honest' and 'dishonest discounters.

In attempting to fix the problem, I tried something that, to the best I can recall, no one else has tried. Previously, all attempts to update MS Office Professional 2021 (64-bit) have produced the same error almost everyone else is reporting. This includes updating from within any Office apps, updating via the Command Prompt, attempting to 'repair' from within Control Panel, and updating by downloading from the MS website. In all these attempts, OneDrive was also active (something I've been trying to get rid of).

Part of why I wanted to get rid of OneDrive (besides all the usual reasons people have) was because I installed a second drive in my laptop, and wanted to configure it as the "data" drive (documents, videos, etc). Once OneDrive has been initiated, Microsoft sure makes it difficult to get ride of AND set up a second drive as a "data" drive. Well, I was finally able to get ride of OneDrive AND get everything set for the second drive to be the "data" drive. Once I had completed all of this, and confirmed that everything else related to the laptop was operating correctly, I logged into my MS account, went to my purchased products, and 'installed' Office 2021 over Office 2021. Once this was complete, I discovered that, instead of Build 17726.20126 (what I had prior to this latest attempt), I now had Build 17830.20138 (ie. the most recent update, Aug 1, 2024).

The 'good' news is, I finally have the most recent version. The 'bad' news is, when clicking "Update Now", it still produces the same popup, with the same 30088-27 error message.

The 'good' news is, I finally have the most recent version. The 'bad' news is, when clicking "Update Now", it still produces the same popup, with the same 30088-27 error message.

Took your lead and got rid of OneDrive (now that I'm sure the error exists with or without it). I have ZERO use for that "service".

BTW, did you just uninstall it or did you do something else? I just uninstall it from Apps.

Ditched OneDrive also. Didn't see much of a point. Definitely not a factor in error 30088-27

and the miracle is over .... our 3 PCs are now here when updating ... I have not even search for it.... I understand Microsoft is not looking over us ... but the MVPs do have a way to seek for help. Time to use it. O365 support is clueless .... so, who do we have to call?

Maybe start throwing garbage at them via social media?