When starting khelpcenter from the install directory instead of the builddirectory, meinproc4.exe is not started according to processmonitor.

The problem seems to be that the kio job to generate the help files is not started.
If I copy the cache files from .kde to .kontact the help opens just fine. Debugging kio seems to be next no impossible, while I can configure debug output going to a file with the uninstalled version, the installed version does not create the debug output file, nor give any indication why it isn't doing that.

Testcase: kioclient.exe cat help:/kmail/index.html

Looks like kio_help.cpp fails somewhere. It get's called at leaset.
Debug output of kio needs to be redirected to files to become visible.

This is the call that somehow fails in kdoctools/xslt.cpp:

xsltParseStylesheetFile

The passed in path to the styleshee (tss) is correct though.

DOCBOOK_XML_CURRDTD just above is certainly invalid (file:///r:/share/xml/docbook/schema/dtd/4.2), but that doesn't seem to affect the problem directly (tried commenting the whole block above).

Same testcase with meinproc:
meinproc4 --stdout "C:/Program Files (x86)/Kontact E5/share/doc/HTML/en//kmail/index.docbook"

And with explicit stylesheet:
meinproc4 --stylesheet "C:/Program Files (x86)/Kontact E5/share/apps/ksgmltools2/customization/kde-chunk.xsl" --stdout "C:/Program Files (x86)/Kontact E5/share/doc/HTML/en//kmail/index.docbook"

This one works though:
meinproc4 --stylesheet "C:/Users/kolab/kderoot/share/apps/ksgmltools2/customization/kde-chunk.xsl" --stdout "C:/Program Files (x86)/Kontact E5/share/doc/HTML/en//kmail/index.docbook"

...and the problem was that kde-include-common.xsl was missing. What a brilliant fucking system.

While the relevant file has now been included in input.nsi, it doesn't seem to get picked up by the installer...