Mend the vault without razing the chamber

Trace the source

Download from the official Prism Launcher vault, not an unmarked mirror.

Break the seal panel

Expand the SmartScreen dialog until Run anyway appears.

Enter only when certain

Choose Run anyway if you trust the artifact, then finish setup.

Install the 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.

Reopen the chamber

Launch Prism Launcher from the Start menu or desktop shortcut.

Open instance settings

Select the instance, then open Settings for that chamber 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 limits

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

Preserve the source archive

Keep the MultiMC instance folder intact before you relocate it.

Use Prism import

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

Re-verify Java and accounts

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

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 excavation log

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