I have Joomla 3.4.3 with the standard protostar template for the frontend. When my site is offline and I'm logging into the frontend (not the adminstrator backend), then I can browse and edit articles.

When I try to save the article by clicking the Save button, nothing happens. The Cancel button does work. On further inspection I found out that there is an

Uncaught TypeError: Cannot read property 'isValid' of null

that is thrown at the outer if condition

Joomla.submitbutton = function(task)
    if (task == 'article.cancel' ||
        if (tinyMCE.get("jform_articletext").isHidden()) {tinyMCE.get("jform_articletext").show()};

I tried finding some solution or related issues, but the only thing that turned up between the clear you browser cache kind of noise was this old issue in an akeeba bug report:

Any ideas what I can do to fix the issue?


It seems that this issue only affects my "About me" article, which is the default article you see when you navigate to my site. Other articles don't seem to have this problem and I can save them from within the front-end.

  • Craig's solution of clearing both Joomla and Browser (Firefox) cache worked for me...
    – Ian Shuter
    Oct 8, 2017 at 21:33

4 Answers 4


I can't reproduce this on a clean install with protostar and TinyMCE.

Is it happening only when site is offline?
On all pages, or on a few or only a single page?

If it's only on a specific pages, see what other extensions exist on that page as it can be a conflict with these. Disable those extensions, clear caches and try again.

Also make sure you have error displaying and debugging set to off when you are trying, as this sometimes may be the cause of such issues.

  • It (currently) appears only on my default home article but with your suggestion I found the problem: On this very page only, I have enabled the Nivo Slider Extension and as I see now, this extension is old and for version Joomla 2.5. Disabling it solves the problem. Let me see whether an update works too.
    – halirutan
    Aug 26, 2015 at 11:13

According to the error, document.formvalidator (media/system/js/validate.js) is not instantiated.

This may be caused by a Javascript conflict in the page or a loading error.

Check if you have any browser console error (for example, a conflict caused by a third-party tinyMCE plugin) or any issue loading the Javascript file.


Funnily enough we had this occur yesterday on a site we're migrating from 2.5 to 3.4.2 (in that case it occurred after updating the template to a point release that came out yesterday).

Clearing both Joomla's cache and the browsers cache resolved the problem for us.

  • I tried this already without success, but I tried it again. No luck, but another very interesting finding came up: It seems to only affect my "About me" article, which is the featured and first article to appear on my site. Let me add this information to my question.
    – halirutan
    Aug 25, 2015 at 23:53

I'm unable to replicate your problem at my end, even by editing the featured and first article. I'd suggest you to delete that About Me article and recreate it again.

  • Didn't work. I assigned a completely different article to this Home menu entry and I still could not save it. It wasn't the article itself, but an extension on my Home menu entry that was enabled only there. See my comment under FFrewin's answer for the full explanation.
    – halirutan
    Aug 26, 2015 at 11:16

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