Guides

Fix one thing without disturbing the rest

Scoped troubleshooting for Prism Launcher — SmartScreen, VC++ runtimes, per-instance Java, MultiMC import, mod failures, and antivirus noise. Each fix stays inside its lane.

LauncherOK

JavaCHECK

AccountOK

Mods2 ISSUES

ImportMultiMC

SmartScreen MSVCP140 Java Import Mods Antivirus

Windows

SmartScreen blocks the installer

Error: Windows protected your PC

Confirm the source

Download from the official Prism Launcher release page — not a repackaged mirror.

Open More info

Expand the SmartScreen dialog so Run anyway becomes visible.

Continue only if trusted

Choose Run anyway, then finish setup into a clean install folder.

Fixed: Reputation warnings fade as more users run the same unsigned build.

Windows

Missing MSVCP140.dll

Error: The program can't start because MSVCP140.dll is missing

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.

Check: Use the official Microsoft redistributable, not a third-party DLL drop-in.

Runtime

Pick the right Java per instance

Open instance settings

Select the instance, then open Settings — changes apply only inside that boundary.

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 — per instance, not globally.

Fixed: A wrong global Java is a common cause of crash loops. Scoped Java fixes the loop without touching other setups.

Migration

Import from MultiMC

Export or copy the instance

Keep the MultiMC instance folder intact before you move it.

Use Prism import

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

Verify Java and accounts

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

Check: Worlds and mods stay under the new instance directory — boundaries preserved.

Gameplay

Mods not loading

Error: Game starts vanilla or crashes during mod init

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.

Fixed: Clean packs from Modrinth or CurseForge reduce version drift inside one instance wall.

Security tooling

Antivirus quarantines the binary

Restore from quarantine

If your AV removed Prism.exe, restore it from the quarantine list.

Add a narrow exclusion

Exclude only the Prism install folder you trust, not an entire drive.

Re-verify checksums

Compare hashes from the release notes before you keep the exclusion.

Check: Heuristic engines sometimes flag game launchers. Source review lives on the Trust page.

Still blocked?

Browse the FAQ for short answers, or review Trust for license and source transparency.

Open FAQ Download again