![](https://mamchenkov.net/wordpress/wp-content/uploads/2018/12/YYYY-1024x393.png)
Erica Sadun blog post goes into details of the difference between ‘YYYY’ and ‘yyyy’ when formatting dates. Remember to add a few unit tests to your application to make sure you are using the correct format.
We’ve recently seen this issue at work and it was a pain in the butt to troubleshoot.