Install Catia V5 R21 On Windows 11 Fixed Official

How to Install CATIA V5 R21 on Windows 11 (Fixed & Working) CATIA V5 R21 is a powerhouse in the engineering world, but it was released long before Windows 11 existed. Because of this, users often face "Side-by-Side configuration" errors, licensing hangs, or abrupt crashes during the installation process.

Settings → Privacy & security → Virus & threat protection → Manage settings → Disable real-time protection.

Install DSLS from \DSLS folder on ISO → Run as Win7 compatibility.
After installation, open DSLS Admin → Stop server → Edit C:\Program Files\Dassault Systemes\DS License Server\conf\dsls.conf → Add line: -Djava.net.preferIPv4Stack=true → Restart server.

SolidSQUAD DSLS_SolidSQUAD emulator v1.6+ works on Win11.
Replace libsat.dll, JS0GROUP.dll in C:\Program Files\Dassault Systemes\B21\win_b64\code\bin\.
Run DSLicSrv.exe as admin → install emulated server on port 4084.

Run CATIA as admin for the first launch:

This is a story about the late-night battle between a determined engineer and a piece of software that refused to acknowledge the modern world. The Clock Strikes Midnight install catia v5 r21 on windows 11 fixed

Check the box for .NET Framework 3.5 (includes .NET 2.0 and 3.0). Click OK and let Windows Update download the files. Install Visual C++ Redistributables: How to Install CATIA V5 R21 on Windows

Final Checklist: