[16.36] Unable to join MP game because of mod settings file

[Kenira]

Only mod installed: Rampant (0.16.23, currently newest version)

Problem description:
We can join each other's games without Rampant installed. With Rampant, we get this error message: https://i.imgur.com/RQ5oCpe.png

We both use the same mod version, we even transferred the mod zip over so we can be 100% sure it's the same. Note that the error message said the mod contents differ despite us using the exact same files, so the error message was wrong about the cause / misleading.

What we expected to happen:
1. Get a proper error message. The mod zip was the same, so saying the mod contents are different is wrong.
2. The mod settings to synchronize, instead of preventing you from playing together completely.

Fix 1:
Deleting my (host) mod settings file.

Fix 2:
Using the same mod settings file on both host and client. However, with my mod settings file, using a differing mod setting file will create the error, so my mod settings file does appear to be the cause for the error somehow.

Steps to reproduce:
-Install Rampant mod (also attached) on both host and client
-Overwrite the mod settings file with the attached mod settings file on the host only
-Host a server
-Try joining the game

I attached the apparently somehow faulty mod settings file, and the version of Rampant we used.

[Loewchen]

Post the log after a session with the error please.

[Therax]

This sounds like it might be a bug in Rampant. Factorio checksums every loaded file to see if you're running the same mod on both server and client, and mods are supposed to always load the same set of files no matter the mod settings. If Rampant is breaking that guideline and somehow loading a different set of files when certain mod settings change, that would cause this behavior.

[Rseding91]

This sounds like it might be a bug in Rampant. Factorio checksums every loaded file to see if you're running the same mod on both server and client, and mods are supposed to always load the same set of files no matter the mod settings. If Rampant is breaking that guideline and somehow loading a different set of files when certain mod settings change, that would cause this behavior.

That's exactly what's happening and why https://wiki.factorio.com/Tutorial:Mod_settings#Tips says:

Do not conditionally 'require(...)' things: This breaks the CRC checks and people will get errors trying to use your mod in multiplayer. 'require(...)' everything and then conditionally add the values to data.raw using the settings.