Knowledge

ERROR_BAD_SERVICE_ENTRYPOINT - 610 (0x262)

{Invalid Service Callback Entrypoint} The %hs service is not written correctly. The stack pointer has been left in an inconsistent state. The callback entrypoint should be declared as WINAPI or STDCALL. Selecting OK will cause the service to continue operation. However, the service process may operate incorrectly.

Updated: Feb 21, 2026

Technical Background

ERROR_BAD_SERVICE_ENTRYPOINT is a specific error code in the Windows operating system, with the numeric value 610 (0x262). This error indicates that a service has been improperly configured due to an invalid callback entrypoint declaration. The stack pointer may be left in an inconsistent state as a result of this issue.

Error Details

The ERROR_BAD_SERVICE_ENTRYPOINT is triggered when the callback function for a Windows service is not declared correctly, typically missing the WINAPI or STDCALL attribute. This can lead to undefined behavior and potential instability in the service's operation.

Common Causes

  • Incorrect Callback Declaration: The callback function for the service is not properly declared as WINAPI or STDCALL. These attributes are crucial for ensuring correct stack cleanup and parameter passing.
  • Service Code Issues: Errors within the service code that affect the callback entrypoint, such as incorrect function signatures or improper handling of parameters.

Real-World Context

This error can occur in a variety of scenarios where services are used to perform background tasks. Services often rely on callback functions for communication with the operating system, and any misdeclaration can lead to critical failures.

Is This Error Critical?

Yes, this error is critical as it can cause the service to operate incorrectly or even crash. The stack pointer inconsistency may result in undefined behavior, leading to potential data corruption or system instability.

How to Diagnose

Reviewing Operation Context

  • Examine the service's codebase for any callback functions that are not declared correctly.
  • Verify that all necessary attributes (WINAPI or STDCALL) are present and used appropriately.

Validating Parameters

  • Ensure that the parameters passed to the callback function match the expected signature.
  • Check for any invalid parameter values that could lead to incorrect behavior.

Confirming Object Types

  • Validate that the service is correctly identifying and handling the types of objects it interacts with, ensuring they are consistent with the expected object types.

How to Resolve

Correct Parameter Usage

  • Ensure all callback functions are declared using WINAPI or STDCALL attributes.
  • Verify that the function signatures match the expected parameter types and counts.

Adjust Operation Context

  • Review the service's configuration and ensure it is operating in an appropriate context. Incorrect operation contexts can lead to misdeclarations of callback functions.

Restore Data

  • If data corruption is suspected, restore any necessary data or reinitialize affected components.

Retry Operation with Valid Inputs

  • Attempt to restart the service or run the problematic operations again with valid inputs to see if the issue resolves itself.

Developer Notes

When developing services that rely on callback functions, it is essential to ensure proper declaration of these functions. This includes using the correct attributes (WINAPI or STDCALL) and ensuring parameter types match the expected signatures.

Related Errors

  • ERROR_INVALID_FUNCTION: Occurs when a function call is invalid due to incorrect parameters or usage context.
  • ERROR_STACK_OVERFLOW: May occur if stack corruption leads to an overflow, which can be indirectly related to improper callback declarations.

FAQ

Q: What does the ERROR_BAD_SERVICE_ENTRYPOINT error mean?

A: It indicates that a service's callback function is not declared correctly, leading to potential stack pointer inconsistencies and undefined behavior.

Q: How can I prevent this error from occurring?

A: Ensure all callback functions are properly declared with the correct attributes (WINAPI or STDCALL) and that parameter types match the expected signatures.

Q: Can this error affect system stability?

A: Yes, it can lead to undefined behavior and potential data corruption, making the service unstable.

Summary

The ERROR_BAD_SERVICE_ENTRYPOINT is a specific error code indicating improper callback function declarations in Windows services. It highlights the importance of correct API usage and proper parameter handling to ensure stable and reliable service operation.