Entry Date field is Required error

Recently all of a sudden I was not able to make new entries or save my edits to one of the channel forms on my EE web site. Every time a hit the Save button, it goes back to edit mode, and I notice the Entry Date field is Required under the Date tab - but the correct date is in there. Very strange.

After searching high and low on the web seeing various suggestions, the correct fix for me is increasing the value of max_input_vars in php.ini. This has something to do with incompatibility between EE 2.6 (version I have) and a newer version of PHP.

I just want to post my solution in here to save others the time as I’m not seeing such a question posted here. Once in a while a new version of PHP causes some headache issues with existing CMS. The nice thing about Wordpress is that the system has a built-in update button that keeps things up to date all the time. EE should have a similar feature.