I have some basic custom modules that use both third party controls and much of my own work.  Now that I've upgraded to 4.8.4, they don't work properly.  Here my issue:

My modules use update panels to control switching between tabs.  But now, when I click a tab, the tabs control doesn't load properly (the tab bar is goes away once used).  The tab control is a third party control which is registered by assembly.  Furthermore, I have images that I reference relatively (for the sake of a portability).  Images on the initial page_load work fine.  But When I click a tab to switch to a different control, the images in the loaded control are broken.  If I change the image reference to a absolute path, it works.

I could deal with making my image references absolute, but it appears my third-party control is also breaking for similar reasons and I can't modify that control.  This works fine in previous versions of DNN and works fine on a regular aspx page.  So something seems different when modules load that changes how things stay connected on updatepanel updates.

Any ideas or similar problems?

That may or may not have been the problem.  I was trumped by someone else doing the upgrading.  I re-upgraded (actually with version 4.9.0) and all is good in the world.  Keeping an eye on web config is helpful though.  Got myself a diff tool.

Thanks,

Ben