You must have full local admin rights.
Administrators use a Hex Editor (like HxD) to find specific patterns. In Windows Server 2019, the goal is often to find the instruction that limits sessions and replace it with a "jump" or a "return true" equivalent. Search: 39 81 3C 06 00 00 0F 84 XX XX XX XX Replace: B8 00 01 00 00 89 81 38 06 00 00 90 Risks and Critical Considerations Windows Updates
Modifying system binaries can lead to "Blue Screen of Death" (BSOD) errors or the total failure of the Remote Desktop service. If the hex code doesn't match your specific build version exactly, the service will fail to start. Security Vulnerabilities windows server 2019 termsrvdll patch patched
Ensure the patched file still has the correct read/execute permissions for the System account.
By bypassing session limits, you may inadvertently bypass other security checks. Additionally, using "pre-patched" files downloaded from the internet is extremely dangerous, as they often contain malware or backdoors. Licensing Compliance You must have full local admin rights
Windows protects system files; you must change the file owner from TrustedInstaller to Administrators .
The Remote Desktop Services service must be stopped during the process. Search: 39 81 3C 06 00 00 0F
💡 For a more stable (and legal) alternative in non-production environments, consider using RDPWrap , though even this tool struggles with the rapid update cadence of Windows Server 2019.
The termsrv.dll file, located in the %SystemRoot%\System32\ directory, is the library responsible for managing Remote Desktop Services. It contains the logic that enforces session limits. In a standard installation, this file checks the OS version and license state to decide how many users can log in at once.
Microsoft frequently updates termsrv.dll to patch security vulnerabilities. When an update occurs, your patched file will likely be overwritten by a new, restricted version. You will need to re-apply the patch or find new hex offsets for the updated version. System Stability
MiddleVR for Unity