The NO_MORE_SYSTEM_PTES bug check has a value of 0x0000003F. This is the result of a system which has performed too many I/O actions. This has resulted in fragmented system page table entries (PTE).

Important This topic is for programmers. If you are a customer who has received a blue screen error code while using your computer, see Troubleshoot blue screen errors.


The following parameters are displayed on the blue screen.



0: system expansion PTE type

1: nonpaged pool expansion PTE type


Size of memory request


Total free system PTEs


Total system PTEs



In almost all cases, the system is not actually out of PTEs. Rather, a driver has requested a large block of memory, but there is no contiguous block of sufficient size to satisfy this request.

Often video drivers will allocate large amounts of kernel memory that must succeed. Some backup programs do the same.


A possible work-around: Modify the registry to increase the total number of system PTEs. If this does not help, remove any recently-installed software, especially backup utilities or disk-intensive applications.

Debugging the problem: The following method can be used to debug bug check 0x3F.

First, get a stack trace, and use the !sysptes 3 extension command.

Then set HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management\TrackPtes equal to DWORD 1, and reboot. This will cause the system to save stack traces.

This allows you to display more detailed information about the PTE owners. For example:

0: kd> !sysptes 4

0x2c47 System PTEs allocated to mapping locked pages

VA       MDL     PageCount  Caller/CallersCaller
f0e5db48 eb6ceef0        1 ntkrpamp!MmMapLockedPages+0x15/ntkrpamp!IopfCallDriver+0x35
f0c3fe48 eb634bf0        1 netbt!NbtTdiAssociateConnection+0x1f/netbt!DelayedNbtProcessConnect+0x17c
f0db38e8 eb65b880        1 mrxsmb!SmbMmAllocateSessionEntry+0x89/mrxsmb!SmbCepInitializeExchange+0xda
f8312568 eb6df880        1 rdbss!RxCreateFromNetRoot+0x3d7/rdbss!RxCreateFromNetRoot+0x93
f8363908 eb685880        1 mrxsmb!SmbMmAllocateSessionEntry+0x89/mrxsmb!SmbCepInitializeExchange+0xda
f0c54248 eb640880        1 rdbss!RxCreateFromNetRoot+0x3d7/rdbss!RxCreateFromNetRoot+0x93
f0ddf448 eb5f3160        1 mrxsmb!MrxSmbUnalignedDirEntryCopyTail+0x387/mrxsmb!MRxSmbCoreInformation+0x36
f150bc08 eb6367b0        1 mrxsmb!MrxSmbUnalignedDirEntryCopyTail+0x387/mrxsmb!MRxSmbCoreInformation+0x36
f1392308 eb6fba70        1 netbt!NbtTdiOpenAddress+0x1fb/netbt!DelayedNbtProcessConnect+0x17c
eb1bee64 edac5000      200 VIDEOPRT!pVideoPortGetDeviceBase+0x118/VIDEOPRT!VideoPortMapMemory+0x45
f139b5a8 edd4b000       12 rdbss!FsRtlCopyWrite2+0x34/rdbss!RxDriverEntry+0x149
eb41f400 ede92000       20 VIDEOPRT!pVideoPortGetDeviceBase+0x139/VIDEOPRT!VideoPortGetDeviceBase+0x1b
eb41f198 edf2a000       20 NDIS!NdisReadNetworkAddress+0x3a/NDIS!NdisFreeSharedMemory+0x58
eb41f1e4 eb110000       10 VIDEOPRT!pVideoPortGetDeviceBase+0x139/VIDEOPRT!VideoPortGetDeviceBase+0x1b

If the system runs out of PTEs again after the TrackPtes registry value has been set, bug check 0xD8 (DRIVER_USED_EXCESSIVE_PTES) will be issued instead of 0x3F. The name of the driver causing this error will be displayed as well.