A recently removed feature of WIndows 11 causes P4 installation to fail. P4 uses SQL Server 2014 Express as the backend database. This is a prerequisite for installing and using P4. SQL Server 2014 requires PowerShell 2.0 to be enabled in Windows 11. PowerShell 2.0 has been deprecated since 2017 but was still included in Windows 11 until an update from August 2025 to version 24H2 removed it entirely from the operating system. Without PowerShell 2.0, SQL Server 2014 and P4 cannot be installed.
P5 was developed as a drop-in replacement for P4 and maintains the same familiar interface and features of P4, with a few enhancements and added features. It also was built on upgraded technology, including SQL Server 2022 Local DB, which does not have the same requirements as SQL Server 2014. If you are unable to install P4, we recommend that you switch to using P5. Also, P4 will be retired on December 1, 2026. See this Microsoft article for more information about the removal of PowerShell 2.0: PowerShell 2.0 removal from Windows - Microsoft Support.