Quality of bibliografic records is important, because it helps users to find books they want. We conducted expert analisis of 100 records form COBIB, survey of users about their use of COBISS/OPAC and COBISS+ and interviews with cataloguers and users about errors in library catalogues. Opinion from users and cataloguers is very interesting. Results show that there were 122 errors. Users in general didn't find errors we showed them, but they said, errors would bother them if these errors were find in titles or authors. Cataloguers were generally satisfied with quality of records in COBIB, but they suggest centralization of cataloguing if we want higher quality of records. We also suggest more seminars and lectures for cataloguers. With this research we got new insight on cataloging errors with opinions of users and cataloguers. This can help to better understand errors and improve quality in catalogues.