It seems you have an outdated version of PortableEngine.Native.dll on your server.

This DLL is embedded in GleamTech.DocumentUltimate.dll and it’s automatically extracted to Temp folder on runtime if it does not exists.

Probably the older version were successfully extracted but the new one can not overwrite the existing one.

The extract may fail

• If the DLL file is in use, so you may need to restart your web server, e.g. via iisreset from command line

• If the permissions on TEMP folder are changed and no longer allowing write and execute permissions.
   You should make sure IIS_IUSRS group has Modify permission on the temp folder 

• - For "ASP.NET Classic":
  -- "%WINDIR%\Microsoft.NET\Framework64\v4.0.30319\Temporary ASP.NET Files\APPNAME\xxxxxxxx"
  -- "%WINDIR%\Microsoft.NET\Framework\v4.0.30319\Temporary ASP.NET Files\APPNAME\xxxxxxxx" (if 32-bit AppPool)
  -- "%LOCALAPPDATA%\Temp\Temporary ASP.NET Files\vs\xxxxxxxx" (when debugging in Visual Studio)
  
  
• - For "ASP.NET Core" the path set in "ASPNETCORE_TEMP" environment variable or result of Path.GetTempPath which depends on "TMP", "TEMP" and "USERPROFILE" environment variables:
  -- "%WINDIR%\Temp"
  -- "%LOCALAPPDATA%\Temp" (if "Load User Profile" is enabled for AppPool in IIS)
  
  
• - For Azure WebApp Service:
  -- "D:\home" (%HOME% environment variable)
  
  
• - For Console or other non-web apps, result of Path.GetTempPath which depends on "TMP", "TEMP" and "USERPROFILE" environment variables:
  -- "%LOCALAPPDATA%\Temp"
  -- "%WINDIR%\Temp"