Outdated templates occur on upgrades when you make an edit inside a template and the parent was changed during the upgrade. It's a way to show you something has been updated in the parent style but it's keeping your changes in your child style. Simple terms you need to open the template and merge the updates with your edits.
Useful tips on avoiding outdated templates:
Avoid editing templates as much as you can, for instance, there's really never a need to edit a CSS/LESS template directly, instead just use the template extra.less for all of your changes.
If you need to add JS/CSS to the header/body area as instructed just use our built-in templates: xb_head and xb_body. These are blank templates that never change so they'll never show as outdated.
You can take advantage of the advertising system for a lot of things. Just because it's called "Advertising" doesn't mean it's just for ads. There are plenty of locations pre-set that you can use to add in custom HTML of whatever you'd like, these never get reset upon upgrading.
You can also take advantage of the widget system, like the Advertising these also don't get reset upon upgrading nor do the edits show as outdated
Fixing outdated templates:
First, try using the automatic merge system, XF has built this to help outdated templates and works well for the most part. Although on more complex outdated templates it may fail and will tell you so.
If it fails, you'll need to process the template by hand. In this example we're looking at PAGE_CONTAINER, I've made a change here, and it's now showing as outdated.
View custom changes:
It'll bring up an overlay, green lines are lines of code are lines in your child style which have been modified/removed in the update, or in this example a custom link we've added:
Scrolling down further we'll see more lines:
This results from the outdated template. A red + green line on top of each means that the line has changed since the updated. Green is what we currently have while red is what should be in the template. You can fix this by hand two ways:
Copy your entire template to have a backup in notepad or another program like it. Click the Revert button so it goes back to the parent version then re-apply your edit. In the case above we're referring to the p-nav--extraLink code, we've added.
Copy the red lines in the overlay and replace the green lines in your template.
Method 1 is handy if there's a ton of changes in the template. 2 is handy if there's just a few like the above example. Once you hit save you can check View changes again if you've merged correctly you should see no red lines of code and just your edit.
No worries... it can seem very overwhelming, we provide an upgrade service. Start a ticket and we can look at the problem, suggest any improvements to avoid the outdated templates and help fix them. While we do this for free in most cases, if you're upgrading from an extremely old version there might be a charge depending on the workload. We'll notify in the ticket.