I moved this topic from WINDOWS general topic list. This is an update. I thank you in advance for reading. UNIFORM SERVER is installed on a Windows Server 2008 R2 virtual machine on a HYPER-V node. I use PHP PDO to write/read data from a PostgreSQL 9.1 database. Sometimes UNIFORM Server stops working and I have to restart it. There are no log in PHP errors log nor in APACHE error log files. After installing new UNIFORM Server 12.0.1 version the problem still exists (read below). I added more informations. The following log is relative to the windows event: Error in d:\w7rtm\enduser\databaseaccess\src\mdac\odbc\core\dm\utsem.cpp(573), The parameter is incorrect. : ReleaseSemaphore failed in UTSemReadWrite:UnlockWrite Log Name: Application Source: Application Error Date: 09/02/2016 07:55:16 Event ID: 1000 Task Category: (100) Level: Error Keywords: Classic User: N/A Computer: xxxxxxxxxxxxxxxxxx Description: Faulting application name: httpd_z.exe, version: 2.4.18.0, time stamp: 0x5667f02e Faulting module name: KERNELBASE.dll, version: 6.1.7601.19110, time stamp: 0x56842600 Exception code: 0xc0000008 Fault offset: 0x0000c42d Faulting process id: 0xf48 Faulting application start time: 0x01d1626d9ca9dc4f Faulting application path: C:\UniServerZ-12-0-1\core\apache2\bin\httpd_z.exe Faulting module path: C:\Windows\syswow64\KERNELBASE.dll Report Id: 129e32bd-cefa-11e5-a654-00155d000176