λ DLL Errors
libgcc_s_seh-1.dll is missing — How to fix it on Windows 11 (2026)
If Windows shows you "libgcc_s_seh-1.dll is missing from your computer" when you launch programs like RPCS3, PCSX2, indie Steam games, the file libgcc_s_seh-1.dll is part of the MinGW-w64 runtime and is almost always fixed by reinstalling that package. This guide walks you through the safe fixes — in the right order.
- Time
- 10 min
- Difficulty
- easy
- Applies to
- Windows 11, Windows 10
- Updated
- May 25, 2026
Error message
The program can't start because libgcc_s_seh-1.dll is missing from your computer. Try reinstalling the program to fix this problem.
Symptoms
- ▸Error popup: "The program can't start because libgcc_s_seh-1.dll is missing from your computer. Try rein…"
- ▸RPCS3 refuses to launch and immediately closes
- ▸Event Viewer logs "Faulting module name: libgcc_s_seh-1.dll"
- ▸Reinstalling the program does not fix the error on its own
Likely causes
- ▸The MinGW-w64 runtime is not installed (or only one architecture is)
- ▸A recent Windows update or program installer corrupted libgcc_s_seh-1.dll
- ▸Antivirus quarantined libgcc_s_seh-1.dll as a false positive
- ▸An older program installed an obsolete copy of libgcc_s_seh-1.dll into its folder
How to fix it — step by step
- 01
Reinstall the MinGW-w64 runtime
libgcc_s_seh-1.dll ships with the MinGW-w64 runtime from MinGW. Uninstall any existing copy from
Settings → Apps, then download the latest x64 and x86 installers from the official MinGW site and install both. Most libgcc_s_seh-1.dll errors stop here. - 02
Run System File Checker
Open PowerShell as Administrator and run the command below. SFC verifies and repairs protected Windows files, including most system-provided DLLs.
sfc /scannow - 03
Repair the Windows component store with DISM
If SFC reports unrepairable files, repair the underlying Windows image first, then re-run SFC.
DISM /Online /Cleanup-Image /RestoreHealth - 04
Reinstall the program that throws the error
If the error appears only when launching programs like RPCS3, PCSX2, indie Steam games, that program installed its own copy of libgcc_s_seh-1.dll into its install folder. Uninstall it through
Settings → Apps, restart Windows, then reinstall from the official source. - 05
Check for malware
Malware often masquerades as a missing DLL. Run a full scan with Windows Defender (
Windows Security → Virus & threat protection → Scan options → Full scan) before downloading any DLL from a third-party site. - 06
Last resort: restore libgcc_s_seh-1.dll from a clean Windows install
If every other step failed, copy libgcc_s_seh-1.dll from
C:\Windows\System32\on another Windows 11 PC of the same architecture (x64 to x64) and the same build. Never download standalone DLLs from "DLL repositories" — they are the #1 vector for adware on Windows.