I've got a rather weird scenario going on here. I am trying to add tooltips to an existing ASP.Net MVC application in which I'm upgrading Bootstrap to 4.6.2. The upgrade was very smooth with no complications; I just want to replace the default display of titles with the nicer looking tooltips, but for some reason they're not appearing. I tried to simplify things by creating a new view to isolate the problem, and still no tooltip. I tried again with completely new solution, and wouldn't you know it, it works! So my question isn't "how do I create tooltips", but "how can I debug what's going on in the failing project?"
Here's what I've discovered so far. I believe you can see everything that's relevant in this screenshot of the nearly-empty view. All the included script files are there in the right order, my script is there, initializing the tooltip, and there are no messages in the console. When I hover over the link, a new <div> element is added to the DOM. In DevTools, I use the arrows to expand the tree, showing everything in the tooltip. The .fade:not(.show) CSS selector is the reason I don't see it. In the working solution, the show class is properly added to the tooltip's <div>.
So, could there be some setting in the existing application preventing the addition of the show class? Is something failing in the tooltip code,causing it to never add the show class without reporting errors? How should I continue debugging this? I tried stepping through the bootstap.js file, but being a JS noob, I'm getting a little lost. The screenshot is from Chrome, but I see the same behavior in Firefox.
This turned out to be one of those embarrassing oversights. My
BundleConfig.csfile was still pointing to old Javascript files that were still hanging around after the upgrade. I should have seen it in the version numbers in the<script>tags.