Some Forge mods are dependent on additional mods to run. This is because sometimes a mod requires a certain library, or is built as an addon to an existing mod rather than as a standalone mod. If an additional mod is required by any mods you have installed, it will be classed as a "Missing Mod", because it is not installed on your server. When there is a missing mod, your server typically won't start or will continue to crash until you have installed the required mod.
When your server crashes due to a MissingModsException, your server will generate a crash report that looks like the following:
In the crash report above, the section you'll need to look for starts on line 5. You will see "Missing Mods:", following by a list of mods and their versions. So in this case, version 1.0.2.13 of Aroma1997Core is missing. Once you've located the missing mod, you can generally can just google it to find a download.
In our case, we can google "Aroma1997Core 1.0.2.13 download" which will lead us to the direct download link on CurseForge.
Once you have uploaded the new required mods to the mods folder, restart your server and connect!
# Missing Mods: Forge
In some instances, the crash report will show a MissingModsException but indicate Forge as missing. The crash report would look something like this:
In the crash report above, it'll specify that Forge is missing. However, Forge isn't a mod but a server type. This error indicates that you have a version of Forge that is not compatible with the mod(s) installed on your server. This either means that you need an older or newer version of Forge.
You will want to look at the line 6 and below, it'll tell you which Forge version your server needs which is Forge: [10.13.4.1614] in the above example. It can be confusing to find which specific version of Forge this is. To narrow down the exact version of Forge you want to look for, you can look for the Minecraft Version specified just below the Details section as shown on the example above.
In our example, it indicates that you need Forge 10.13.4.1614 for Minecraft 1.7.10. Download this specific version required from https://files.minecraftforge.net.
You can then follow our tutorial on How to Install Forge on your Minecraft Server.
