"reactos-cov\modules\rostests\winetests\msi\msi_winetest.rc(2): error RC2135: file not found: custom.dll [C:\ros_build\modules\rostests\winetests\msi\msi_winetest.vcxproj]".
Output files are written to Debug\ and Release\ subfolders in VSSolution mode, so the RC compiler will only find custom.dll if it knows to look in the right folder.
Thanks to Thomas Faber, who helped.
CORE-11836