After I upgraded to 10.5, I noticed in the ArcGIS 10.5 Help that the webpage about Client and geodatabase compatibility suggests that ArcGIS releases below 10.5 may be incapable to connect to a 10.5 File Geodatabase. 10.5 is not listed for the 10.1-10.4.x releases.
Now I guess this may be an oversight in the Help, especially since the Create File GDB tool does not list a new option for creating <10.5 release File Geodatabases, except the ones that were already available at 10.4.x (10.0/9.3/9.2), but since I don't have an older setup to test this, can someone tell me whether 10.5 File Geodatabases can be read by older versions of ArcGIS? I am aware of the general concept of no new functionality being available when accessing from an older client, I am just interested to know whether the Help is in error here.
Using ArcPy with ArcGIS 10.5, we can see that the file geodatabase version remains the same as from 10.0 - 10.4.x.
>>> folder = # path to temp folder
>>> fgdb = arcpy.CreateFileGDB_management(folder, "fgdb_105", "CURRENT")
>>> desc = arcpy.Describe(fgdb)
It also looks like 10.5 ArcPy Describe Workspace properties has not been updated to reflect that 10.5 also uses the 3,0,0 release of the file geodatabase.
Thanks Joshua. That's a good one! I have been learning ArcPy and Python quite well over the past three years, but there always remain these hidden corners you haven't explored yet. I hadn't realized such a method existed.
File geodatabase format itself hasn't changed in a long time, but geodatabase capabilities of ArcGIS have changed. So the answer is likely to be "Yes, it will work, if you're not using a 10.5-specific data structure."