Stabilize the crossing without collapsing a dimension

Confirm the source

Use GitHub release links from this mirror — not unofficial download mirrors.

Open More info

Expand the SmartScreen dialog so Run anyway appears.

Continue only if trusted

Choose Run anyway, then finish the installer.

Install VC++ Redistributable

Install the latest Microsoft Visual C++ Redistributable (x64) for your Windows build.

Reboot if prompted

Some systems need a restart before the DLL path updates.

Launch again

Start Prism Launcher from the Start menu or desktop shortcut.

Open dimension settings

Select the instance, then open Settings for that dimension only.

Assign a Java path

Point to a JDK or JRE that matches the Minecraft version (often Java 17 or 21 for modern packs).

Set memory

Raise max memory for large packs, but leave headroom for the OS.

Preserve the old dimension

Keep the MultiMC instance folder intact before you cross it over.

Use Prism import

Pick the MultiMC / Prism-compatible import path in Add instance.

Verify Java and accounts

Re-check loader version, Java path, and Microsoft account after the crossing.

Confirm loader match

Forge mods need Forge; Fabric mods need Fabric. Mixed jars fail quietly or loudly.

Match Minecraft version

A 1.20.1 mod will not run on a 1.21 instance without a compatible build.

Read the log

Open the instance log and remove the first missing dependency or bad jar.