As I posted back in November, the setup of an add-in for the VBA editor of Office 2013 written with VB6 could fail with the following error:
“Unable to register DLL/OCX:RegSvr32 failed with exit code 0x5”
I mentioned that the cause was that the file Msaddndr.dll is no longer installed by Office 2013 and today I have found that Microsoft wrote an official Knowledge Base (KB) article stating it a month later:
A custom add-in that uses interfaces in the Msaddndr.dll file does not work in Office 2013
The workaround is, of course, that your setup installs that file. BTW, I got yesterday a bug report from a user of my MZ-Tools 3.0 for VBA with that same error but using a MZTools3VBASetup.exe that already (supposedly) installed the file. It happened that the system already had that file installed, but an old version, and the setup only installed it if not present, so it was not replaced by the newest version. So, when applying this workaround, ensure that your setup installs the file if not present, or if it is an older version, because it seems that there are at least two versions of Msaddndr.dll out there.