After installing ArcGISPro_23_167023.exe, NOT for all users, just myself, installation folder defaulted to my user directory, instead of C:\Program Files\ArcGIS\
Then, installing ArcGIS_Pro_233_168940.msp failed at every attempt, whether as a "software update" in ArcGIS Pro, or running the downloaded MSP.
First, 1304 error, followed by 2349 error.
Neither error appears in the UpdateLog.txt (attached)
Prompted to make sure I "had access to" the folder, I did indeed have access, that was not the problem.
Following tips in https://community.esri.com/discussion/create.jspa?containerType=14&containerID=2151 I turned off virus scanning and firewall, that was not the problem, either.
Reinstalled Pro "for all users", in default C:\Program Files\ArcGIS\
Patch installed without errors.
Strange then, the only difference I can see is when I installed Pro and upgrades, I didn't use Users, but I install directly in:
Other fluff goes into Users
C:\Users\... name ...\AppData\Local\ESRI
C:\Users\... name ...\AppData\Local\ESRI\conda
Strange behavior. The documented install location for a per-user install is here:
https://pro.arcgis.com/en/pro-app/get-started/arcgis-pro-installation-administration.htm (that's the location whether you install silently or not. Pro 2.4 doc will be updated to make these locations more clear).
If you need the software installed only for you, not all users on the machine, and are running into errors, please reach out to Technical Support: https://support.esri.com/en/contact-tech-support