How to fix "Invalid format of field 'X'"

From the biblatex documentation:

2.3.8 Date Specifications

The date fields date, origdate, eventdate, and urldate require a date specification in yyyy-mm-dd format. Date ranges are given as yyyy-mm-dd/yyyy-mm-dd. Partial dates are valid provided that date components are omitted at the end only. You may specify an open ended date range by giving the range separator and omitting the end date (e. g., yyyy/). See table 2 for some examples of valid date specifications and the formatted date autmatically generated by biblatex. The formatted date is language specific and will be adapted automatically. If there is no date field in an entry, biblatex will also consider the fields year and month for backwards compatibility with traditional BibTeX. Style author should note that date fields like date or origdate are only available in the bib file. All dates are parsed and dissected into their components as the bib file is processed. The date components are made available to styles by way of the special fields discussed in § 4.2.4.3. See this section and table 7 on page 126 for further information.

Using the biber backend for biblatex like so

\usepackage[backend=biber]{biblatex}

also lets you use the three-letter abbreviations in your bib file.

If you are on Ubuntu > 12.10 you can install biber by clicking the button below

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