I have an elderly application I’m trying to keep limping along until its replacement is ready. This application runs on two machines. One of the machines works well, but the other is only somewhat working, where some things are fine but certain background feature silently fail.
On the machine that is not working I can see messages in a log file for the application like this:
An error was encountered in clsData_DTS.ImportFile while importing file: (Class not registered).
or
Error in
clsData_ImportFile.DTSDatawhile importing …
So I know some class names (clsData_DTS.ImportFile) and I strongly suspect these are VB classes in a COM dll that is corrupt or incorrectly registered. There are a few similar errors with different class names.
But good news: the application is working on the other computer, so given the class name I hope to use the other computer to find the associated dll to use to replace and re-register the same file on the failing machine.
Searching the registry on the good machine for class name or any segment of the class name turns up nothing.
How can I find which dll implements this class?
It’s worth mentioning now this application was originally run on 32-bit Windows XP, but is now running on 64-bit Windows 10 on both machines. We do need to use compatibility settings to keep it working, but both are set to run as administrator with compatibility for XPsp3. We no longer have the original installer for this application; the last time we had to copy files and register dlls by hand 🥶, but the process has worked for some time… so it is probably worth doing the detective work to fix this rather than re-install.
