In old versions of PB there was no need to register the sybase excel dlls for their .net excel save as. This appeared to have changed sometime between 12.6 and 2017R3.
I've seen some conflicting information on whether it supposed to be required to register those dlls into the GAC. (typical installation methods would include runtime dlls with exe, gac registration should be required only if those dlls are stored elsewhere).
The bug fixes for build 2323 do not list anything about the GAC requirements changing, but a response to a bug report seems to indicate that starting with 19R3 build 2323 the GAC is no longer required?
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"BTW, the issue is fixed in the PB 2019 R2 Build 2323:
copy the Sybase.PowerBuilder.DataWindow.Excel12.dll to your application folder
and don't using the GAC install and try it again."
Yes, its still the same requirement as in PB 12.x. If you copy the "Sybase.PowerBuilder.DataWindow.Excel12.dll" to your App's EXE folder then that is all you need to do for the deployment.
If you install the "Sybase.PowerBuilder.DataWindow.Excel12.dll" to a *different* folder other than the PB App's EXE - then you must register the .NET DLL in the GAC.
Regards ... Chris