I'm not a developer so I don't know the correct terms to describe this properly so apologies in advance if this isn't very clear.

I'm in the process of building my site which is using K2 and Simple Image Gallery Pro. Initially I was having problems with SIG Pro in that the thumbnails would appear in the gallery at the bottom of a K2 item but when you clicked on them they wouldn't open. This appeared to be down to a JQuery conflict. I changed a few settings in SIG, using a different JQuery version and a different engine and that seemed to clear the problem and for a few days SIG and K2 items displayed fine.

Every now and then though I would find that when I went to view a K2 item in the front end that I had just created it wouldn't load and it would just look like the CSS hadn't loaded but also there wouldn't be any content either. All I would see would be a text version of the main menu, my website logo and a search box .Like this:


Typically I found that if I just refreshed the page it would load correctly so i just put it down to a cache issue.

However yesterday I added about a dozen new K2 items and after I added the last one I found that NO K2 items would load. I've tried clearing the website cache, browser cache, using different browsers, different computers and even different ISP's but nothing works. The main front page of the site loads fine as do NON K2 articles but any K2 Item I click on results in the image above. I haven't installed any other components/modules/plugins in between it working and it not working. It was literally working one minute and then seconds later completed stopped and the only thing I had done in between was to click on Save on the K2 item I had just created which was just text and one image.

When I view any of the K2 items in the backend they all look fine but in the front end Firebug reports:

ReferenceError: jQuery is not defined
"NetworkError: 500 Internal Server Error

When viewing non K2 articles, no such errors are reported.

I should also point out that I have created my K2 Items using Joomla Shine Pagebuilder however I have also tried creating a new K2 item using JCE Editor and exactly the same thing happens.

I found that to get SIG working I needed to use jQuery 1.11 with colorbox engine and loading jQuery from JQuery CDN. In K2 Parameters I've tried using the same jQuery version and think I've tried just about every available option but nothing seems to make any difference (and each time I change a setting a clear the cache).

In searching here I found someone with a similar problem and it was suggested that they move the K2 plugin to be just above the page-cache plugin (mine K2 plugin was almost at the top). I've tried moving it and it made no difference.

I've no idea what else to try now.

Well I've found out what the cause was but not why.

I am using the Breadcrumb module in my site and for some reason this has completely packed up working in K2 (it was working fine for a few hours at least). The module works fine for non K2 items but is now causing a 500 server error for K2 items.

Is there a dedicated K2 Breadcrumbs module? I'm probably going to use K2 to completely replace the standard Joomla article system but there may be the odd article that I'd like to keep separate. Is there a breadcrumb module that will work with both K2 and Joomla articles?

Yes there is.
You can use the K2 Tools module which includes breadcrumbs functionality.