Walking through doors

Category: KAG Server
Operating system: Linux
Build number: ### (Number of build in which the bug was encountered.)
Description: See below.
Steps to reproduce: Unknown.
Screenshots/Videos: None, sorry.

Code:

[23:22:41] Bad delta!
[23:22:41] Bad snapshot; skipping 73b fail 12 (last packet 50 once 71 debug archer)
[23:22:41] Bad delta!
[23:22:41] Bad snapshot; skipping 73b fail 11 (last packet 50 once 71 debug archer)
[23:22:41] Bad delta!
[23:22:41] Bad snapshot; skipping 73b fail 10 (last packet 50 once 71 debug archer)
[23:22:41] Bad delta!
[23:22:41] Bad snapshot; skipping 73b fail 9 (last packet 50 once 71 debug archer)
[23:22:41] Bad delta!
[23:22:41] Bad snapshot; skipping 73b fail 8 (last packet 50 once 71 debug archer)
[23:22:41] Bad delta!
[23:22:41] Bad snapshot; skipping 73b fail 7 (last packet 50 once 71 debug archer)
[23:22:41] Bad delta!
[23:22:41] Bad snapshot; skipping 73b fail 6 (last packet 50 once 71 debug archer)
[23:22:41] Bad delta!
[23:22:41] Bad snapshot; skipping 73b fail 5 (last packet 50 once 71 debug archer)
[23:22:41] Bad delta!
[23:22:41] Bad snapshot; skipping 73b fail 4 (last packet 50 once 71 debug archer)
[23:22:41] Bad delta!
[23:22:41] Bad snapshot; skipping 73b fail 3 (last packet 50 once 71 debug archer)
[23:22:41] Bad delta!
[23:22:41] Bad snapshot; skipping 73b fail 2 (last packet 50 once 71 debug archer)
[23:22:41] Bad delta!

I think you get the idea.

That's what my server log looks like.
In game, I could walk through doors of the enemy. Only I could do this. No door animation would play. Killing myself did not resolve the issue. My client is the Steam Mac version.

Delta, I suspect, has to with collisions? I dabbled in multiplayer code once, it sounds familiar.