Hi @John D
Generally speaking, it's okay for SSRSto have a lower version number than SQL server, but since SSRS has been separated from SQL server since version 2017, I don't know if this is compatible, but I think it should be compatible. you can upgrade SQL server first , then see if SSRS 2014 can work normally, if it works well,then don‘t need to upgrade the SSRS. if not, upgrade SSRS to SSRS2017 or SSRS 2019.
Here is official document about how to upgrade the SSRS ,you can take a reference:https://learn.microsoft.com/en-us/sql/reporting-services/install-windows/upgrade-and-migrate-reporting-services?view=sql-server-ver16
Upgrade to Reporting Services 2017 and later from Reporting Services 2016 and older isn’t the same upgrade scenario as in previous versions. When upgrading to Reporting Services 2016 and older versions, you could following an in-place upgrade process using SQL Server installation media. When upgrading to Reporting Services 2017 and later from Reporting Services 2016 and older, you can’t follow the same steps because the new Reporting Services installation is a standalone product. It's no longer part of the SQL Server installation media.
To upgrade from Reporting Services 2016 and older versions to Reporting Services 2017 and later, follow the Migrate a Reporting Services Installation (Native Mode) article, with Reporting Services 2017 or later as your destination instance.
Best Regards,
Isabella
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