Event ID 535 — TBS Operation

Applies To: Windows Server 2008

This version of Windows includes TPM Base Services (TBS), a component similar to an Application Programming Interface (API) , that allows the operating system and application programs to communicate with and share the use of a Trusted Platform Module chip in the computer. The BitLocker Drive Encryption feature uses the TPM by default. Failures or unexpected results encountered by the TBS can result in the TBS or the TPM driver logging event messages.


Event Details

Product: Windows Operating System
ID: 535
Source: Microsoft-Windows-TBS
Version: 6.0
Message: A new TBS context could not be created because there are too many open contexts.


Restart the application or the computer

In order to successfully use services provided by the Trusted Platform Module, applications (including components of Windows, such as BitLocker) communicate with the TPM by using TPM Base Services (TBS) and an application programming interface (API), and must receive the expected results. Each application using TBS may expect the TPM to be in a particular state.

To resolve this condition, try each of the following steps, as required:

  • Close the application and then re-open it.
  • Restart the computer.

If this error condition continues and none of the above steps resolves the issue, try each of the following steps, as required:

  • Ensure that the TPM hardware is functioning correctly.
  • Verify that the application is compatible with this version of Windows.
  • Verify that the application is compatible with the version of the TPM that is installed.

In these cases, contact your hardware manufacturer, software publisher, or support team, as appropriate.


To perform this procedure, you must have membership in Users, or you must have been delegated the appropriate authority.

To verify the correct operation of TBS:

  1. Restart the computer.
  2. Verify that all applications and components that use the TPM, such as BitLocker Drive Encryption, work correctly without errors appearing on screen or in the Event log. Specifically, the following steps can verify the correct operation of BitLocker:
    • Verify that Windows Welcome Screen, Logon Screen or Desktop appears. This indicates that BitLocker has correctly unlocked the Windows operating system volume.
    • Log on to Windows and access any data volumes that are encrypted with BitLocker.

Note: Data volumes can be configured to be automatically unlocked or to require manual unlocking.

TBS Operation

Core Security