We’re not ready to upgrade our server to 19, but would like to upgrade some clients to 19. I understand that we won’t be able to leverage any of the new functionality of 19, but will there be any issues with accessing a database hosted on FMS18 with FMP19?

I can't say definitively, but I am using FM19's new Javascript integration feature even though the database is hosted on FMS18.

As far as I can recall I've always been able to utilise the client where the FMS host was one version lower (the exception being when we switch to .fmp12 extension).

Furthermore, when I finally did upgrade the server to match the clients I did not notice any improvements.

Edited June 14, 20205 yr by sal88

You can keep the databases on FMS 18 and still use new JavaScript functions in FMP 19.

Oh, that's great!  We're not planning on using any of the new functionality in 19.  Rather, just want to upgrade certain clients to 19, with the database remaining on FMS18 (and otherwise unchanged).