STOP c000021a 0xc0000005: How to Fix

c000021a 0xc0000005 error frequently occurs during logon or logging off. The problems tends to appear after applying a Service Pack.

c000021a 0xc0000005 During Logon

Some users recommend the following technique that helped them fix the problem.

  • Restart in Safe Mode
  • Press return key when asked for passwords.
  • Go to User accounts and delete or change any passwords found (not users accounts!)

In some cases that fixed the problem.

Logging on a domain on a Windows 2000-based computer

When you attempt to log on to a domain on a Windows 2000-based computer, first you are briefly displayed Winlogon error dialog box, then the system crashed with the following STOP error message:

STOP: c000021a (Fatal System Error) The Windows Logon Process System process terminated unexpectedly with a status of 0xc0000005 (0x0000000 0x00000000). The system has been shut down.

You may encounter this error when FQDN (the fully qualified domain name) of your computer is exactly 200 bytes long. When you logon, heap corruption occurs because one character more than the 200-byte allocation is written.

You can fix this problem either by renaming the computer so that the name is shorter than 200 bytes. Alternatively, you can use a hotfix provided by the Microsoft Company:

  • Date: 24-Oct-2002
  • Time: 01:33
  • Version: 5.0.2195.6102
  • Size: 46,864
  • File name: Secur32.dll

Applying a service pack for Windows NT 4.0

You may receive stop c000021a 0xc0000005 error combination after you apply a service pack for Windows NT 4.0, the error message on the blue screen looks like this:

Stop: c000021a {Fatal System Error} The session manager initialization system process terminated unexpectedly with a status of 0xc0000005 (0x00000000, 0x0000000)

The problem is caused by corrupt Windows NT system files which were copied when service pack was applied. Specifically, if the the service pack update program displayed a message that a certain file (for example, Ntdll.dll if you were running Compaq's Insight Managewas on Compaq servers) was busy, skipped the copy of this file may result in the above error. To fix the problem, you have to replace the corrupt/skipped file with the updated file from the Service Pack.

If your system files are on a volume with NTFS file system:

  • Make a parallel install of Windows NT Service Pack 2. and overwrite the old Ntdll.dll with the updated file from Service Pack 2.

If your system files are on a volume with FAT file system:

  • boot to an MS-DOS bootable disk and replace Ntdll.dll with the version from Windows NT 4.0 Service Pack 2.
  • Replace corrupt system file with the help of Emergency Repair Disk

Possible Code Combinations: