Stoneopolis modpack Minecraft server

Stoneopolis is a question-based modpack for Minecraft 1.20.1 on Forge, by the CurseForge author benbenlaw. Its page describes a custom world made of stone with empty caves, more than 100 game stages that hide progression until you unlock it, and mods such as Caveopolis, Blood Magic and Immersive Engineering. You install the server from the Modpacks tab, using the pack's CurseForge listing.

Checked against Stoneopolis 4.2 on Forge 47.2.20 and Minecraft 1.20.1, 27 October 2026.

What the pack needs

• Game and loader. Minecraft 1.20.1 with Forge 47.2.20, both named in the pack's manifest.json. The panel runs it on Java 17.
• Version 4.2. The newest file, 4.2, has no server pack on CurseForge, so Newest that fits your server builds the server from its mod list. The install turns off DefaultWorldType, the mod that sets the pack's world type on players' computers, but it first reads that mod's setting and gives the server the same world type. Have players install Stoneopolis 4.2 so their mods match the server.
• Memory. benbenlaw says a 4 GB plan suits Stoneopolis, and the 4.2 install adds 140 mods. The panel sizes the heap from your plan's RAM; how much RAM a Minecraft server needs explains the trade-offs.

Install the server

Press the CurseForge chip in Modpacks, search for Stoneopolis and pick Stoneopolis. The popup names Forge and Minecraft 1.20.1. If it has a version dropdown, leave it on Newest that fits your server, which takes 4.2. The window lists one mod to download first, CoolCatLib: get it with its Download from CurseForge button and drop it in, as Modpack mods to download from CurseForge shows, or tick Install without them (add them later from this tab). When this guide was checked, the server started without it. The backup, the EULA and the rest of the window are covered in Install a CurseForge modpack.

The pack ships no server engine, so the install sets up Forge 1.20.1-47.2.20, the build the pack's manifest.json names. Then press Start on the Console and wait for For help, type.

The world and settings

With no server pack, the install writes a short server.properties of its own, and the console says World type skyblockbuilder:skyblock, from the pack's Default World Type setting. The first start makes a void world, with no land around the spawn point. The spawn island appears when the first player joins.

The 4.1 server pack also set max-players=10, allow-flight=true and max-tick-time=120000. The 4.2 install does not, so the server starts with Minecraft's defaults. To match the author's values, set Player slots, Allow flight and Watchdog timeout (ms) in Config Editor.

Common problems

• A player cannot join. They need Stoneopolis 4.2 on Minecraft 1.20.1 with Forge, and if they have it, compare their mod list with the server's mods folder.
• The server will not finish booting. The crash report names the mod at fault: find and read a crash report.