Question Blank page when I try to create media object

I am using webtrees v 1.7.17.
I am using Control Panel Media menu functions.
I used 'Upload Media Files' to upload a JPG image. 
In 'Manage Media Files' (Unused Files) the image shows up, and all looks correct.
I believe I now have to create a Media Object.
Under Media Objects I click the Create Link - it shows a popup window which is competely blank. View Page Source on this window also shows that is completely blank.

See attached screenshots.

Any help would be greatly appreciated.
 

I would use a current version of webtrees.

v1.7 is an old version, but I have used it until recently.

What I never did was use the Control Panel to manage media. It is a needless complex workflow.

Simply edit a fact/event and use the button (or link?) "add media" to upload a new picture or reuse an existing one (by typing its title)
Portraits can be added via the Media tab of persons.

You need to check file size limits prior to uploading. That may be 1mb by default while it is easily much more these days. Search here on the forum on "file upload size limit" for clues.

> I would use a current version of webtrees.

This!

Alternatively, try webtrees.net/faq/500/

If it is just a problem with one image, then perhaps it is too large?

Images I tried are quite small (300kB, and 18kB).

I can upload them, but can't make media objects from them.

 

Yes, I will try to upgrade to new version, but might not be able to do it for a week or 2.