Google Sitemap Error - Invalid Date

Google Sitemap Error - Invalid Date

This error means that your sitemap contains an entry which has an invalid last modified date. Google Sitemaps requires the ISO-8601 encoding which has two variations:

- 2005-02-21

This one just contains the year (4 digit), the month (2 digit) and the day (2 digit)

- 2005-02-21T18:00:15+00:00

This one is more complex and includes the year (4 digit), the month (2 digit) and the day (2 digit) followed by the character "T", the hour (2 digit), colon, minute (2 digit), colon, second (2 digit) and finally the time zone with the character "+" OR "-", the timezone offset in hours (2 digit) and minutes (2 digit).
It's important to include ALL parts of the chosen date format and pay attention to the correct order.