@Efriim said in Installing Retropie on Raspian RPI3 B+:

Will the new OpenGL drivers ever be compatible, is it up to emulationstation devs? or will the emulators not work too? Does Pegasus-FE work with Opengl?

Most of the emulators (and Emulationstation) are using the - native - OpenGL ES stack available on RPI, which doesn't need an X.org and has direct hardware acceleration. IMHO there's little advantage in using OpenGL instead of the native stack, but I haven't run any benchmarks.
The downside of using the - new - OpenGL driver is that certain utilities that rely on the native driver (tvservice for instance) might not work and functionality that's right now included in RetroPie would not be available.
You can find the original discussion here.

This helped and I believe solved the problem once I tweaked my config options. Thanks so much.

I don't think that it is specific to the Xbox dongle. I am having the same issue and found this on the rpi github. It looks like the kernel is having a hard time with USB hubs.

F/W 4.14.x causes dwc_otg_handle_mode_mismatch_intr:68: messages on boot with C-Media Electronics Inc. USB PnP Sound Device