No content shows. Only code as text string when selecting "Apply" / "Cancel" of any Views Pop-up window.

Problem/Motivation

Returned text string rather than content, when Admn selects "Apply" or "Cancel" at end of Views pop-up editing.

Steps to reproduce

1. Open any View for editing;
2. Select "Edit view name";
3. Select "Cancel" (see image *1a) .
4. Code as text string appears (see image *2a):
5. Updated to Views 7 3.27. No change (see file *3a).
6. Updated to Views 7 3.Dev No change (see file *4a).
7. May this have any connection (An ajax error)?
When running update.php I get:
An AJAX HTTP request terminated abnormally. Debugging information follows. Path: https://www.inlowgear.co.il/update.php?op=selection&token=e1UZen1GrEQNlw... StatusText: error ResponseText: ReadyState: 0

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes