Set up the Mustard Virus server

Mustard Virus is a zombie apocalypse modpack for Minecraft 1.12.2 on Forge, listed on CurseForge as Mustard Virus by Forge Labs. Its page describes endless waves of infected that are drawn to light, sound and players, and that sunlight no longer harms. You install it from the Modpacks tab, but the project holds two generations of files and the tab picks the older one unless you choose, so read the next section first.

Checked against Mustard Virus 2.1 (the CurseForge file dated 31 October 2021) on Forge 14.23.5.2855 and Minecraft 1.12.2, October 2026.

What the pack needs

• Minecraft 1.12.2 with Forge 14.23.5.2855. Minecraft 1.12.2 runs on Java 8, and the panel picks the Java version from the pack's Minecraft version, so there is nothing to choose.
• Memory. The pack's page gives no RAM figure. Your plan sets the RAM, so see how much RAM a Minecraft server needs and the Minecraft plans.
• The same pack for players. Players install the same file from the CurseForge app.

Pick the right file

The project has two kinds of file. Zombie Apocalypse Slow Version 1.7 (March 2021) comes with a server pack of about 146 MB (139.0 MB on CurseForge's file page, which counts in MiB). Mustard Virus 2.1(FOR NEW MAP ONLY) (October 2021) has no server pack, only a list of 34 mods and their configs. The author's changelog on the 2.1 file reads "Update that supports the map from the NEW video(Surviving the Hardcore Zombie Apocalypse). Continue using V1.7 if you have the 100 Days map."

With nothing chosen, the tab installs the newest file that has a server pack, which is 1.7. To get 2.1, choose the file yourself as shown below.

Install the server

1. Open your server and choose Modpacks under Content in the left rail.
2. Above the search box, press the CurseForge chip and search for Mustard Virus. Pick Mustard Virus by Forge Labs.
3. Press Install. The popup says it reinstalls your server and names Forge and Minecraft 1.12.2.
4. To install 2.1, open the version dropdown in the popup, which reads Newest that fits your server, and choose Mustard Virus 2.1(FOR NEW MAP ONLY). The dropdown's list only fills for the Minecraft version the store is filtered to, so if it is empty, press Modrinth, set the Game version filter to 1.12.2, press CurseForge again and reopen Install. The version dropdown only shows where our updated installer is switched on for your account. If you do not see it, you will get 1.7.
5. Leave Take a backup first ticked, because your current world is replaced. Tick Start the server when it's ready if you want it to start by itself, and I agree to the Minecraft EULA if the popup shows it.
6. Hold Install and reinstall until it fills, then wait for the install to finish.

Version 2.1 has no server pack, so the installer reads the pack's mod list, downloads the mods from the pack's list of 34 (leaving out any it can tell are client-only), then installs Forge 14.23.5.2855 itself. When this guide was checked, every one of the 34 listed mods had a direct download, so the popup should ask you for none.

The 2.1 file carries no world. The author's changelog says it supports the map from their newer video, and uploading a singleplayer world covers putting a map on your server.

First start

Press Start on the Console tab and accept the Minecraft EULA if the panel asks. The server is up when the console prints a line containing For help, type. Your address is in the left rail with a copy button beside it. Connect to your server for the first time covers adding it in Minecraft, and joining a modded server from a launcher covers the client side.

Common problems

• A player cannot join. Check they run the same pack file as the server, on Minecraft 1.12.2 with Forge.
• The install fails. Check Disk Analyser in case the plan's disk is full, clear space and install again. Where the updated installer is on for your account, press Last install log on the Modpacks tab to read what failed.
• The server crashes at boot. Find and read a crash report shows how to name the mod at fault.
• The server lags. Watch the RAM card on the Console tab and the TPS reading in the left rail, and read why is my server lagging.