[Koha] Importing staged records stops at #53849 (Koha 3.00.01.005)

[Marc Nürnberger]

Dear List,

I am struggling with the webinterface import of staged MARC records:
The import seems to stop invariably at rec #53849.

Oddly enough, there seems to be no broken MARC record near this 
number. I can indivually import all the records around it including 
#53849, and even if I delete these five from the import file, so that 
they are replaced by other records, it just happens again: no 
importing beyond MARC #53849.

Any ideas?

Best regards,
Marc