Package natbib error: Bibliography not compatible with author year citation

LaTeX error message upon build:

Natbibbibliography not compatible with author year citation
In my case this was caused by a missing year entry in a bib-entry in Mendeley. This caused something along these lines in bibliography.aux (important is the last line missing a year column):
\\bibcite{Wurman.2000}{{27}{2000}{{Wurman}}{{}}}
\\bibcite{Wurman2001}{{28}{2001}{{Wurman et~al.}}{{}}}
\\bibcite{Xerox2008}{{29}{{Xerox Corporation}}{{}}}
The second cause might be, that your bibliography file contains special characters and isnt correctly UTF8 encoded.
So you have basically 2 options here:
Either manually solve it in the bibliography file
add the missing year to whatever bib entry is missing that datum (either directly in the .bib file or indirectly in jabref or e.g. mendeley)
make sure special characters in the file are encoded using UTF8
clear your bibliography.aux file
rebuild
Or change the citation style
change