Information about missing entry point error installing legacy VB6 compiled applications on Windows 10 which I hope could be useful to someone.
Missing OCX files can be found in the "OS\System folder" of the Visual Basic 6.0 installer package.
Today I copied the relevant OCX file (from our network) to the local computer
And then I typed the commands below, as administrator, which normally work to register it.
cd \windows\syswow64
regsvr32.exe /u mscomctl.ocx
regsvr32.exe /i mscomctl.ocx
(add the path to the locally copied file for the /i command)
However today I got errors from both these regsvr32.exe commands.
The second error was giving the DllImport missing entry point error which is similar to the error mentioned by the original poster.
To resolve, one of the things I tried was leaving out the switch -
regsvr32.exe mscomctl.ocx
To my surprise it then said it was successful.
To confirm, the application started up properly afterwards.