Bad value 480 for attribute rel on element a

@maciejmt – Can you provide an live URL where this is appearing?

– Cais.

https://www.largosystem.pl/pl/produkty/kolect-program-do-katalogowania-banknotow/

@maciejmt – I can see a JavaScript error on your site via the Chrome developer tools but I am not seeing anything referencing your OP …

– Cais.

and? The rel value is generated from your plugin ??
I also have Chrome and don’t see any JS errors.

@maciejmt – This screen snippet was taken from your home page: https://take.ms/BKPmr … I don’t recognize what may be causing it to happen but it is there all the same.

– Cais.

NextGEN Gallery version 2.0.79
It is the Lightbox module generating this code with rel attribute incompatible with HTML5. It is in case you have activated Fancybox or Thickbox. Assuming you have the plugin installed find this file:
/wp-content/plugins/nextgen-gallery/products/photocrati_nextgen/modules/lightbox/package.module.lightbox.php
Then search for rel= and replace it with some data attribute, for instance data-fancybox-group=
Now the Fancybox line should look something like this:
$fancybox->code = 'class="ngg-fancybox" data-fancybox-group="%GALLERY_NAME%"';
Use the same principle for Thickbox if needed.

Sorry for my previous post, it isn’t the final solution, because the grouping doesn’t work. I was in rush and didn’t test it properly. Still trying to solve the problem.

In addition to my previous instructions you have to edit at least the file /wp-content/plugins/nextgen-gallery/products/photocrati_nextgen/modules/lightbox/static/fancybox/jquery.fancybox-1.3.4.pack.js (version may differ), find/replace all rel to data-fancybox-group. There should be 3 of them. This will make the existing galleries to work properly and validate in W3C.

You may need to apply similar find/replace the rel in this file too /wp-content/plugins/nextgen-gallery/products/photocrati_nextgen/modules/nextgen_settings/module.nextgen_settings.php , but as mentioned it isn’t required for existing galleries.

In place of data-fancybox-group you can use something shorter like data-fboxg etc, but as you already guess it must be done everywhere you replaced the rel.

@jyriii – Thanks for sharing. We bundle the current Lightbox libraries with NextGEN Gallery as a convenience. As we do not specifically support these libraries this will be helpful for those concerned with what W3C thinks of their site.

– Cais.

@cais – I understand, thanks. That’s right, I just posted it here for the same reason, to provide quicker help.

About the W3C compliance, note that webmasters can understand which validation errors are important and which ones are not, but if the client will complain, it can be hard to explain them. Today everybody love SEO.

All the best

@jyriii – I can appreciate some users not really understanding the information they are presented, especially if it is out of context … education is key.

– Cais.