Biblatex/Biber suddenly outputs 'invalid format of date field'

Question

UPDATE: Deleting the Cache using

rm -rf `biber --cache`

solved my problem.

I'm a new user of LaTeX and use it the first time to write a thesis. Up until now I had everything running fine and was polishing my text as my citations didn't process anymore. I use Biblatex and Biber and export my literature automatically from Zotero.

This is a example:

\documentclass[a4paper,11pt,headsepline]{scrartcl}
\usepackage{fontspec}
\setsansfont{Arial}
\renewcommand\familydefault{\sfdefault}
\usepackage[ngerman]{babel}
\usepackage[right]{eurosym}
\usepackage{geometry}
\geometry{left=3cm, right=4cm, top=3cm, bottom=3cm}
\usepackage[backend=biber, style=apa]{biblatex}
\addbibresource{Literatur.bib}
\begin{document}
This is some Text.
And a really important citation \parencite{neugebauer2020}.
The \textcite{rkimeasles2020} has some totally important findings.
\end{document}

With these in the .bib file:

@article{neugebauer2020,
  title = {Beurteilung des neuen Masernschutzgesetzes in Deutschland: Ergebnisse einer deutschlandweiten Befragung},
  shorttitle = {Beurteilung des neuen Masernschutzgesetzes in Deutschland},
  author = {Neugebauer, Michael and Ebert, Matthias and Vogelmann, Roger},
  date = {2020-11-25},
  journaltitle = {Zeitschrift für Evidenz, Fortbildung und Qualität im Gesundheitswesen},
  volume = {158-159},
  pages = {74--80},
  issn = {18659217},
  doi = {10.1016/j.zefq.2020.10.009},
  url = {https://zefq-journal.com/article/S1865-9217(20)30171-9/abstract},
  urldate = {2021-01-27}
}
@misc{rkimeasles2020,
  title = {{{RKI}}-Ratgeber - {{Masern}}},
  editor = {{Robert Koch-Institut}},
  date = {2020},
  url = {https://www.rki.de/DE/Content/Infekt/EpidBull/Merkblaetter/Ratgeber_Masern.html},
  urldate = {2021-01-04},
  file = {/Users/dennis/Zotero/storage/AJTINZFI/Ratgeber_Masern.html}
}

Running this using Texmaker (Xelatex -> biber -> Xelatex outputs this:

Process started

Unicode::UCD: failed to find unicore/version in /var/folders/sn/mrxx700x6wjbb_wbvjt1_x480000gn/T/par-64656e6e6973/cache-2f8a664c3c933a44d096bcc8d018a5e92bced897/inc/lib /var/folders/sn mrxx700x6wjbb_wbvjt1_x480000gn/T/par-64656e6e6973/cache-2f8a664c3c933a44d096bcc8d018a5e92bced897/inc CODE(0x7f871ef8cad8) CODE(0x7f871ef8d0c0) at /var/folders/sn mrxx700x6wjbb_wbvjt1_x480000gn/T/par-64656e6e6973/cache-2f8a664c3c933a44d096bcc8d018a5e92bced897/inc/lib/Biber/Internals.pm line 1238.

INFO - This is Biber 2.14 INFO - Logfile is 'Testtex.blg' INFO - Reading 'Testtex.bcf' INFO - Found 2 citekeys in bib section 0 INFO - Processing section 0 INFO - Globbing data source 'Literatur.bib' INFO - Globbed data source 'Literatur.bib' to Literatur.bib INFO - Looking for bibtex format file 'Literatur.bib' for section 0 INFO - LaTeX decoding ... INFO - Found BibTeX data source 'Literatur.bib' WARN - Entry 'neugebauer2020' (Literatur.bib): Invalid format '2020-11-25' of date field 'date' - ignoring WARN - Entry 'neugebauer2020' (Literatur.bib): Invalid format '2021-01-27' of date field 'urldate' - ignoring WARN - Entry 'rkimeasles2020' (Literatur.bib): Invalid format '2020' of date field 'date' - ignoring WARN - Entry 'rkimeasles2020' (Literatur.bib): Invalid format '2021-01-04' of date field 'urldate' - ignoring

Process exited with error(s)

Running with Latexmk or Biber directly gives me the same Warnings about the invalid date format.

Biber warning: [217] Utils.pm:304> WARN - Entry 'neugebauer2020' (Literatur.bib): Invalid format '2020-11-25' of date field 'date' - ignoring

I'm at a loss here. From my point of view the date format is correct. I also tried deleting the Biber Cache. No Change.

Any ideas?