It would be super helpful if you had provided exact error message text/screenshot along with step on which you getting error (outline of the steps can be found here). If you have reached Database Configuration page and specified SQL server which hosts your K2 5.2 DB I see no reason for SQL compatibility error. But I guess presense of local SQL server installation may trigger this warning. Just share error message screenshot here that may clarify what exactly is happening.

Thank you, I've attached what the installer looks like and the error that gets reported. Note that it is only the client components that are installed and being updated, there should not be any dependency on SQL Server for these as I was able to install them with the 4.7 installer without issue.

So error reports that you have SQL server build10.50.2500.0 which means SQL Server 2008 R2 Service Pack 1 (SP1) which is 100% not something that K2 Five supports.

Does your K2 Five database hosted on SQL 2008 R2 SP1 server? I think no, but it can be that while you have SQL Server 2012 or newer yet you not upped your database compatibility level on K2 database, so maybe check this (see screenshot below which illustrates what exactly you need to check using SSMS UI).

Yes. my K2 server is using SQL server 2016 correctly and I had no issues upgrading the server - that is why I a most confused. Where is it looking on my developer workstation to determine that SQL server is out of date if I don't even have SQL server installed? Does it look at K2 Servers I've connected to in the past, perhaps?

I would consider logging support ticket attaching installer trace. A bit difficult to comment on that without having install trace and/or ability to have a look at the environment.

Yep, that's what I ended up doing. I'll report back what they discover. Thanks!