Error 42 is one of the few, possibly the only one, without a decent text description. It means there was a problem building the browse info database (<projectname>.tag).
Version 5.0 of Pelles C use SQLite v3.x, the previous version used SQLite v2.x. A mix of database versions may cause this error (and this is the only case I am aware of), but there might be other cases. Try deleting the <projectname>.tag file and rebuild the project to see what happens...