@darkman Tested now with newest German-Language-Pack, same Result as without Lang-Pack: Disabling "System - JCE" solves Problem.

Sorry for no better News.

Hi there,

I posted the problem at JCE and Ryan send me this reply:

This is actually the result of a bug in K2, which will be fixed in K2 2.7.
I have however made some changes to the System - JCE plugin to prevent this error.

Replace jce.php in /plugins/system/jce/ with the file in the attached zip.

The link to the file: www.joomlacontenteditor.net/support/forum/item-must-have-a-title

regards Ronald

Awesome! Thank you Ronald (and Ryan)

The patch for K2 is located here: github.com/joomlaworks/k2/commit/4bbfd5cf0cf3911dbbf5393a4bcd882ec111ff99

We are having this same problem in Joomla 3.4.4.It also will not allow us to type in the title field. But the K2 Version is already 2.7 and the JCE patch did not help. Turning off JCE does not help. I
Is there anything else we can try?

Hi Weatherly,

just to be at the Point: if you write "Turning off JCE" you mean "System - JCE" (Plugin)?

Regards

Yes. System JCE Plugin

After comparing files I see that even though the backend says its 2.7 and the files have it at the top, the changes on the patch page were not implemented. Adding them fixed it.
However I am seeing another issue apparently caused by 2.7: typing in the title box is invisible. It appears this to be caused by this :in the media assets k2 css file: .k2TitleBox {
box-sizing: border-box;
width: 100%;
font-size: 14px !important;
padding: 10px 10px !important;}
Is this something new to 2.7 (so far as i know we hadn't touched it)? It seems to conflict with the Isis media template.

@Weatherly Which browser are you using?