Neither error.log nor debug.log show any entry.
Just overwriten functions-basic again - to make sure I didn't miss anything - and again, no entries in the log-files.
But: I just realised, that the BE is not reachable when this file is replaced.
Regarding php 5.x: I am aware of it and action will be taken, once ZP is up and running live. - that's the current plan