Can I upgrade my ArcGIS Server from 10.2.1 using a Web Adaptor but not Portal directly to ArcGIS Server 10.5?
If I upgrade my SQL Server 2008 R2 to SQL Server 2012 Service Pack 3, would this make this possible?
You should keep versions installed on the same machine at the same version.
re: Server, yes you should be able to upgrade from 10.2.2 to 10.5 Frequently asked upgrading questions—Installation Guides (10.5) | ArcGIS Enterprise
Web adaptors themselve do not upgrade...those need to be reinstalled/created, but fwiw, I have web adaptors from different AGS and Portal versions installed on the same IIS instance...with different names of course.
re: SQL Upgrade an enterprise geodatabase in SQL Server—Help | ArcGIS Desktop
as posted by George Thompson in another thread this morning 10.5 Upgrade Geodatabase option grayed-out
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