No problem here. Did you upgrade the tools at the same time as Blender? Probably restarting Blender has already fixed this for you.

Wish it did. I must once again specify that even installing BST errors blender out. I will reinstall blender then

Reinstalled Blender, the addon installs fine. However, importing SMD animations is still not possible:

Python: Traceback (most recent call last):
File "C:\Users\CoolGuy\AppData\Roaming\Blender Foundation\Blender\5.0\scripts\addons\io_scene_valvesource\import_smd.py", line 77, in execute
bpy.context.view_layer.objects.active = self.qc.a

File "C:\Users\CoolGuy\AppData\Roaming\Blender Foundation\Blender\5.0\scripts\addons\io_scene_valvesource\import_smd.py", line 1238, in readSMD
if target_arm:

File "C:\Users\CoolGuy\AppData\Roaming\Blender Foundation\Blender\5.0\scripts\addons\io_scene_valvesource\import_smd.py", line 424, in readFrames
phantom_parent = smd.phantomParentIDs.get(phantom_parent)

File "C:\Users\CoolGuy\AppData\Roaming\Blender Foundation\Blender\5.0\scripts\addons\io_scene_valvesource\import_smd.py", line 590, in applyFrames

File "C:\Users\CoolGuy\AppData\Roaming\Blender Foundation\Blender\5.0\scripts\addons\io_scene_valvesource\import_smd.py", line 537, in ApplyRecursive

AttributeError: 'Action' object has no attribute 'groups'

This issue affect all smd animation files, both when importing them via qc, and when importing directly. I'll have to downgrade Blender for now, but please look into it, don't brush it off.