Error: net.minecraftforge.fml.common.LoaderException: java.lang.RuntimeException: Error syncing field 'permissionMode' of class 'c4.colytra.common.config.ConfigHandler'!

Occurs when loading mods in startup sequence. Deleting the Config file does not fix the issue, and installing earlier versions doesn't help either, even though with the 1.0.3 version there is no issue at all.

Is there a more specific config file I should be deleting?

Something's going on with your loader that's causing it to somehow cache old config files, or somehow you didn't really delete it. This error is due to the presence of a field called 'permissionMode' that is present in the config file but doesn't match the data in the config class, which can only happen if the config is already there when the loading starts.

If you really regenerated the config file, then check the file itself. The field should look this:

    # Sets whether the Item List uses a blacklist or a whitelist
    # Valid values:
    # BLACKLIST
    # WHITELIST
    S:"Permission Mode"=BLACKLIST

If it doesn't look exactly like that, then something went wrong with your loader or you accidentally downloaded an older version. If it does look like that and you're still getting the error, I honestly wouldn't have any idea what's going on. Have you tried versions 1.0.4.x? Those should definitely be working because it was before I implemented the related change.

I'll check it out!

Is the correct file path through c4\colytra\common\config\ ?

Is the correct file path through c4\colytra\common\config\ ?

No, that's the class path, which you shouldn't be touching at all. Are you trying to access the jar itself? Because all you need to do is go into your root minecraft folder, wherever the mods folder also is, and go to the config folder and delete colytra.cfg.

Found it! I had assumed the .cfg would be in the .jar, since a lot of mods place theirs in it. Completely forgot that Minecraft has its own little config folder!

Thanks for the help, this error has been fixed, however I am now getting a probably unrelated error.
Error: java.nio.file.ClosedFileSystemException which is just a wrong version error for an incorrectly installed mod. Dope.

I don't know your exact setup, but I'll just say as a mod developer that most mods do not put their config files in the jar and that you should not be messing with any jar at all. The config folder is there precisely for mod configs and that should be where you'll find the vast majority of config files, barring mods that need additional special configuration or data writing.

As for that error, I don't know how that came about but I can only suggest that maybe you should redownload all your mods in case you've messed with something in the jars that broke the loading.

Sorry, yeah I was thinking Skyrim and Fallout style config setup with the config files being located within the sections containing the main mod assets and code (I haven't played Minecraft in about a year with HEAVY modding on those two games meanwhile)
I had an "invalid" version of Forge or something. I had installed the 2792 v. which isn't on the Forge versions list and 2793 v. fixed the issue. Also had one mod for 1.13
Thanks for correcting me, wouldn't want to make that mistake again!