Not able to create a link in the content creation area.

Could you check for Javascript errors in your browser when you can’t create links?
https://codex.www.ads-software.com/Using_Your_Browser_to_Diagnose_JavaScript_Errors

That should help us find out more about the issue.

I would also suggest that you switch to one of the default themes for a few minutes, and let me know if it helps.

The error happens in multiple browsers.

I added the JavaScript debug check to the wp-config file.
In Chrome. I went to one of my simpler pages (the about page that has a few links and text) opened Inspect Element and went to Console. Clicked the TinyMCE add/edit link, and received this message.

Uncaught TypeError: Cannot read property ‘show’ of undefined wplink.js?ver=4.0:111wpLink.open wplink.js?ver=4.0:111(anonymous function) plugin.js:8N.execCommand tinymce.min.js?ver=4104-20140822:9t.cmd.t.onclick tinymce.min.js?ver=4104-20140822:9r tinymce.min.js?ver=4104-20140822:7e.extend.fire tinymce.min.js?ver=4104-20140822:7e tinymce.min.js?ver=4104-20140822:7i tinymce.min.js?ver=4104-20140822:2m tinymce.min.js?ver=4104-20140822:2

Switching to Twenty Fourteen theme:

Uncaught TypeError: Cannot read property ‘show’ of undefined wplink.js?ver=4.0:111wpLink.open wplink.js?ver=4.0:111(anonymous function) plugin.js:8N.execCommand tinymce.min.js?ver=4104-20140822:9t.cmd.t.onclick tinymce.min.js?ver=4104-20140822:9r tinymce.min.js?ver=4104-20140822:7e.extend.fire tinymce.min.js?ver=4104-20140822:7e tinymce.min.js?ver=4104-20140822:7i tinymce.min.js?ver=4104-20140822:2m tinymce.min.js?ver=4104-20140822:2

Here are other findings from a page using video.

In Firefox I checked:
Tools -> Web Developer -> Web Console
(likely the newer version of Tools > Web Developer > Error Console mentioned on the JavaScript Errors page)

TypeError: inputs.wrap is undefined wplink.js:111
TypeError: wrap is undefined wp-auth-check.js:96
Error: Permission denied to access property ‘toString’ post.php:41
TypeError: wrap is undefined wp-auth-check.js:96
Error: Permission denied to access property ‘toString’ post.php:41
TypeError: wrap is undefined wp-auth-check.js:96
TypeError: wrap is undefined

In Chrome:

JQMIGRATE: Logging is active jquery-migrate.js:21
Uncaught SyntaxError: Unexpected token * quickedit_functions.js:1
Consider using ‘dppx’ units, as in CSS ‘dpi’ means dots-per-CSS-inch, not dots-per-physical-inch, so does not correspond to the actual ‘dpi’ of a screen. In media query expression: print, not all, (-webkit-min-device-pixel-ratio: 1.25), (min-resolution: 120dpi) post.php?post=66&action=edit&message=1:492
Uncaught SyntaxError: Unexpected token * eml-media-models.js:1
Uncaught SyntaxError: Unexpected token * eml-media-views.js:1
Uncaught SyntaxError: Unexpected token * aioseop_module.js:1
Uncaught SyntaxError: Unexpected token * admin.js:1
JQMIGRATE: jQuery.fn.live() is deprecated jquery-migrate.js:41
console.trace() jquery-migrate.js:43migrateWarn jquery-migrate.js:43
Uncaught ReferenceError: countChars is not defined post.php:942
Consider using ‘dppx’ units, as in CSS ‘dpi’ means dots-per-CSS-inch, not dots-per-physical-inch, so does not correspond to the actual ‘dpi’ of a screen. In media query expression: print, not all, (-webkit-min-device-pixel-ratio: 1.25), (min-resolution: 120dpi) post.php?post=66&action=edit&message=1:1
‘HTMLVideoElement.webkitSupportsFullscreen’ is deprecated. Its value is true if the video is loaded.
Uncaught TypeError: Cannot read property ‘show’ of undefined wplink.js:111
Failed to load resource: net::ERR_CACHE_MISS

Check the Opera instructions on the JavaScript page.
I right clicked and did an inspect element, and clicked Console.

JQMIGRATE: Logging is active jquery-migrate.js?ver=1.2.1:21
Uncaught SyntaxError: Unexpected token * quickedit_functions.js:1
Consider using ‘dppx’ units, as in CSS ‘dpi’ means dots-per-CSS-inch, not dots-per-physical-inch, so does not correspond to the actual ‘dpi’ of a screen. In media query expression: print, not all, (-webkit-min-device-pixel-ratio: 1.25), (min-resolution: 120dpi) post.php?post=66&action=edit:490
Uncaught SyntaxError: Unexpected token * eml-media-models.js:1
Uncaught SyntaxError: Unexpected token * eml-media-views.js:1
Uncaught SyntaxError: Unexpected token * aioseop_module.js:1
Uncaught SyntaxError: Unexpected token * admin.js:1
JQMIGRATE: jQuery.fn.live() is deprecated jquery-migrate.js?ver=1.2.1:41
console.trace() jquery-migrate.js?ver=1.2.1:43migrateWarn jquery-migrate.js?ver=1.2.1:43
Uncaught ReferenceError: countChars is not defined post.php?post=66&action=edit:940
Consider using ‘dppx’ units, as in CSS ‘dpi’ means dots-per-CSS-inch, not dots-per-physical-inch, so does not correspond to the actual ‘dpi’ of a screen. In media query expression: print, not all, (-webkit-min-device-pixel-ratio: 1.25), (min-resolution: 120dpi) post.php?post=66&action=edit:1
Opera has modified script or content on https://www.youtube.com (PATCH-1185, youtube.com – show video above playlist). See browser.js for details browser.js:65
Opera has modified script or content on player.vimeo.com (PATCH-1166, vimeo.com – make click-to-play and turbo mode work). See browser.js for details browser.js:65
‘HTMLVideoElement.webkitSupportsFullscreen’ is deprecated. Its value is true if the video is loaded.
Opera has modified script or content on player.vimeo.com (PATCH-1166, vimeo.com – make click-to-play and turbo mode work). See browser.js for details browser.js:65
Opera has modified script or content on player.vimeo.com (PATCH-1166, vimeo.com – make click-to-play and turbo mode work). See browser.js for details browser.js:65
Opera has modified script or content on https://www.youtube.com (PATCH-1185, youtube.com – show video above playlist). See browser.js for details browser.js:65
Opera has modified script or content on https://www.youtube.com (PATCH-1185, youtube.com – show video above playlist). See browser.js for details browser.js:65
Opera has modified script or content on https://www.youtube.com (PATCH-1185, youtube.com – show video above playlist). See browser.js for details browser.js:65
Uncaught TypeError: Cannot read property ‘show’ of undefined wplink.js?ver=4.0:111
Opera has modified script or content on player.vimeo.com (PATCH-1166, vimeo.com – make click-to-play and turbo mode work). See browser.js for details browser.js:65
Opera has modified script or content on https://www.youtube.com (PATCH-1185, youtube.com – show video above playlist). See browser.js for details browser.js:65
Opera has modified script or content on player.vimeo.com (PATCH-1166, vimeo.com – make click-to-play and turbo mode work). See browser.js for details browser.js:65
Opera has modified script or content on https://www.youtube.com (PATCH-1185, youtube.com – show video above playlist). See browser.js for details browser.js:65
2Uncaught TypeError: Cannot read property ‘show’ of undefined wplink.js?ver=4.0:111
Opera has modified script or content on https://www.youtube.com (PATCH-1185, youtube.com – show video above playlist). See browser.js for details browser.js:65
Opera has modified script or content on https://www.youtube.com (PATCH-1185, youtube.com – show video above playlist). See browser.js for details browser.js:65
Opera has modified script or content on https://www.youtube.com (PATCH-1185, youtube.com – show video above playlist). See browser.js for details browser.js:65
2Uncaught TypeError: Cannot read property ‘show’ of undefined wplink.js?ver=4.0:111
Failed to load resource: net::ERR_CACHE_MISS https://player.vimeo.com/video/70771444
Failed to load resource: net::ERR_CACHE_MISS https://player.vimeo.com/video/83055841
Failed to load resource: net::ERR_CACHE_MISS https://player.vimeo.com/video/83055071
Failed to load resource: net::ERR_CACHE_MISS https://player.vimeo.com/video/83056048
Failed to load resource: net::ERR_CACHE_MISS https://player.vimeo.com/video/76520522

I also checked another page
onsider using ‘dppx’ units, as in CSS ‘dpi’ means dots-per-CSS-inch, not dots-per-physical-inch, so does not correspond to the actual ‘dpi’ of a screen. In media query expression: print, not all, (-webkit-min-device-pixel-ratio: 1.25), (min-resolution: 120dpi) post.php?post=16&action=edit:29
6Consider using ‘dppx’ units, as in CSS ‘dpi’ means dots-per-CSS-inch, not dots-per-physical-inch, so does not correspond to the actual ‘dpi’ of a screen. In media query expression: print, not all, (-webkit-min-device-pixel-ratio: 1.25), (min-resolution: 120dpi) post.php?post=16&action=edit:31
JQMIGRATE: Logging is active jquery-migrate.js?ver=1.2.1:21
Uncaught SyntaxError: Unexpected token * quickedit_functions.js:1
Consider using ‘dppx’ units, as in CSS ‘dpi’ means dots-per-CSS-inch, not dots-per-physical-inch, so does not correspond to the actual ‘dpi’ of a screen. In media query expression: print, not all, (-webkit-min-device-pixel-ratio: 1.25), (min-resolution: 120dpi) post.php?post=16&action=edit:491
Uncaught SyntaxError: Unexpected token * eml-media-models.js:1
Uncaught SyntaxError: Unexpected token * eml-media-views.js:1
Uncaught SyntaxError: Unexpected token * aioseop_module.js:1
Uncaught SyntaxError: Unexpected token * admin.js:1
JQMIGRATE: jQuery.fn.live() is deprecated jquery-migrate.js?ver=1.2.1:41
console.trace() jquery-migrate.js?ver=1.2.1:43migrateWarn jquery-migrate.js?ver=1.2.1:43
Uncaught ReferenceError: countChars is not defined post.php?post=16&action=edit:875
Consider using ‘dppx’ units, as in CSS ‘dpi’ means dots-per-CSS-inch, not dots-per-physical-inch, so does not correspond to the actual ‘dpi’ of a screen. In media query expression: print, not all, (-webkit-min-device-pixel-ratio: 1.25), (min-resolution: 120dpi) post.php?post=16&action=edit:1
Uncaught TypeError: Cannot read property ‘show’ of undefined wplink.js?ver=4.0:111

Uncaught TypeError: Cannot read property ‘show’ of undefined wplink.js?ver=4.0:111

Thank you. It would seem that the jQuery library is not properly loaded in your dashboard at the moment.

Could you try to switch to one of the default themes for a few minutes, and let me know if it helps?

Ok I changed again to Twenty Fourteen, and went to my about page. Right clicked to open Inspect Element in Chrome and checked the Console. Clicked the create link in TinyMCE and here is the console error message that came up.

Uncaught TypeError: Cannot read property ‘hasClass’ of undefined VM211 load-scripts.php?c=1&load%5B%5D=hoverIntent,common,admin-bar,schedule,wp-ajax-response,autosa…:1028(anonymous function) VM211 load-scripts.php?c=1&load%5B%5D=hoverIntent,common,admin-bar,schedule,wp-ajax-response,autosa…:1028m.event.dispatch VM191 load-scripts.php?c=1&load%5B%5D=jquery-core,jquery-migrate,utils,jquery-ui-core,jquery-ui-wid…:3r.handle VM191 load-scripts.php?c=1&load%5B%5D=jquery-core,jquery-migrate,utils,jquery-ui-core,jquery-ui-wid…:3m.event.trigger VM191 load-scripts.php?c=1&load%5B%5D=jquery-core,jquery-migrate,utils,jquery-ui-core,jquery-ui-wid…:3e.event.trigger VM191 load-scripts.php?c=1&load%5B%5D=jquery-core,jquery-migrate,utils,jquery-ui-core,jquery-ui-wid…:8(anonymous function) VM191 load-scripts.php?c=1&load%5B%5D=jquery-core,jquery-migrate,utils,jquery-ui-core,jquery-ui-wid…:3m.extend.each VM191 load-scripts.php?c=1&load%5B%5D=jquery-core,jquery-migrate,utils,jquery-ui-core,jquery-ui-wid…:2m.fn.m.each VM191 load-scripts.php?c=1&load%5B%5D=jquery-core,jquery-migrate,utils,jquery-ui-core,jquery-ui-wid…:2m.fn.extend.trigger VM191 load-scripts.php?c=1&load%5B%5D=jquery-core,jquery-migrate,utils,jquery-ui-core,jquery-ui-wid…:3(anonymous function) VM211 load-scripts.php?c=1&load%5B%5D=hoverIntent,common,admin-bar,schedule,wp-ajax-response,autosa…:61j VM191 load-scripts.php?c=1&load%5B%5D=jquery-core,jquery-migrate,utils,jquery-ui-core,jquery-ui-wid…:2k.fireWith VM191 load-scripts.php?c=1&load%5B%5D=jquery-core,jquery-migrate,utils,jquery-ui-core,jquery-ui-wid…:2x VM191 load-scripts.php?c=1&load%5B%5D=jquery-core,jquery-migrate,utils,jquery-ui-core,jquery-ui-wid…:4b VM191 load-scripts.php?c=1&load%5B%5D=jquery-core,jquery-migrate,utils,jquery-ui-core,jquery-ui-wid…:4
Uncaught TypeError: Cannot read property ‘show’ of undefined VM211 load-scripts.php?c=1&load%5B%5D=hoverIntent,common,admin-bar,schedule,wp-ajax-response,autosa…:1037wpLink.open VM211 load-scripts.php?c=1&load%5B%5D=hoverIntent,common,admin-bar,schedule,wp-ajax-response,autosa…:1037(anonymous function) wp-tinymce.php?c=1&ver=4104-20140822:52N.execCommand wp-tinymce.php?c=1&ver=4104-20140822:10t.cmd.t.onclick wp-tinymce.php?c=1&ver=4104-20140822:10r wp-tinymce.php?c=1&ver=4104-20140822:8e.extend.fire wp-tinymce.php?c=1&ver=4104-20140822:8e wp-tinymce.php?c=1&ver=4104-20140822:8i wp-tinymce.php?c=1&ver=4104-20140822:3m wp-tinymce.php?c=1&ver=4104-20140822:3

Thanks. The problem doesn’t seem related to your theme. It does seem to be caused by a plugin adding elements to the TinyMCE editor.

Can you identify the plugin that’s causing it? If you deactivate all of your plugins and re-enable them one at a time that should help you get to the bottom of it.

Let me know how it goes.

Sigh…. even though I had earlier turned off all the plugins except Jetpack it still did not work (turning off all plugins except the one with the problem is a standard procedure). Now something else happened and I found the plugin that was causing the problem and will e-mail the developer about this.

Thanks for your guidance Jeremy!
It helped a lot!