7.2: Errors in collection building

Sometimes things go wrong during collection building. Maybe some files couldn't be processed: the rest of the collection builds fine, and can be previewed, but some documents are absent. Or the whole collection is not built properly, in which case a message says "An error has occurred and the collection could not be created." When this happens, it may be helpful to switch the GLI into expert mode (File->Preferences->Mode, see Preferences), set the build option "verbosity" to 5, and rebuild, to see if there are any error messages.