I've just recently encountered a weird error / bug in SharePoint. Here is the scenario:

- I have a custom column "Test Date" that is of DateTime field type. The field is configured as REQUIRED.

- It is added to a custom Content Type "Test CT" that is based on a "Publishing Page" content type

- I have created a Page Layout "Test PL" which is based on that particular content type.

Now here is what happens:

1. I try to create a page based on both that Content Type and Page Layout in the Pages Library. I manage to create it successfully.

2. However, when I go to try and edit the page, fill-in the required values and try to save it using the PAGE TAB -> SAVE BUTTON, I get the below error/s. Note that this happens no matter what I choose in the drop-down menu for Save Button.

**"The file XXX has been modified by USER on DATE"**

But I know I am the ONLY user modifying the page. 

*If I try to save again it gives me options to whether Discard my Changes, Keep Editing, Overwrite Changes, or Merge.*

- HOWEVER, if I use the Save button on the UPPER RIGHT corner of the screen (the shortcut). I am able to save successfully without any errors!

The only thing I've tried that made it work was if I made the DateTime OPTIONAL. But I need it to be REQUIRED.

Is there any workaround to this error / bug?

Thanks