Incompatibility error with Krastorio 2 (1.3.15), BrassTacks (1.1.5):
Error ModManager.cpp:1560: Error in assignID: item with name 'complex-joint' does not exist.
Source: utility-science-pack (recipe).

Changing "utility-science-pack" to "utility-tech-card" in compat/final.lua, line 54, fixes the error for me.

After some more digging into it, I tried first installing version 1.1.4, loading the world and then updating to 1.1.5. It seems to have fixed my issue. Maybe something goes wrong when starting on version 1.1.5 instead of 1.1.4 and updating and it doing the migration of the 'complex-joint' name change.

Still getting this error in the current version of the mod (and K2 and Factorio).

Factorio version: 1.1.80
K2 version: 1.3.18

Screenshot of error:
https://imgur.com/a/g0ZQcVL

Following up on this -- if you install K2 and Space Exploration, the error does not occur. Maybe something in SE's "final fixes" or similar is catching the error?

Oh this is an easy fix. I originally thought it was some sort of version mismatch thing or a corrupted download since I could never reproduce it, but apparently I never tried the very obvious likely cause - the complex-joint item only exists if you enable a setting to add more intermediates, and which I apparently entirely forgot to put a check for when modifying K2 utility science specifically.

The simple reason SE fixes this is I don't modify the utility science recipe if SE is installed, because SE changes the context of utility and production science and adding complex joints to the recipe no longer makes as much sense flavorwise.

The update I just pushed should fix the issue, let me know if the error continues.

Seems to work now. I am also sure you figured it out correctly, because I had just figured out I could fix it myself by enabling the intermediates in the settings, then installing K2.

Thanks!