RPC_S_INVALID_TAG - 1733 (0x6C5)
The tag is invalid.
Updated: Feb 21, 2026
Introduction
The RPC_S_INVALID_TAG error (1733, 0x6C5) is a specific error indicating that an invalid tag was encountered during the execution of a Remote Procedure Call (RPC) operation. This article provides detailed technical information and guidance for developers encountering this error.
Technical Background
Remote Procedure Calls (RPCs) are a protocol for communication between processes, often used in distributed applications. The RPC_S_INVALID_TAG error is related to parameter validation within the RPC framework, specifically when an unexpected or invalid tag is detected during message processing.
Error Details
The error code RPC_S_INVALID_TAG signifies that a tag passed as part of an RPC request was not recognized by the system. Tags in this context are identifiers used to distinguish between different types of data within an RPC message, such as parameters or return values.
Common Causes
- Invalid Parameter Values: The tag passed is not valid according to the expected format or type for the operation being performed.
- Incorrect Object Type: The object referenced by the tag does not match the expected type required by the RPC operation.
Real-World Context
This error typically occurs when an application attempts to make an RPC call with improperly formatted tags, leading to a failure in message processing. It is important for developers to ensure that all parameters passed to RPC operations are correctly formatted and validated before being sent.
Is This Error Critical?
The criticality of this error depends on the specific context in which it occurs. While not necessarily catastrophic, it can indicate issues with application logic or data integrity, potentially leading to further errors if left unaddressed.
How to Diagnose
To diagnose RPC_S_INVALID_TAG, developers should:
- Review Operation Context: Ensure that the RPC operation being performed is appropriate for the current context and environment.
- Validate Parameters: Check all parameters passed to the RPC call, particularly those containing tags, against expected formats and types.
- Confirm Object Types: Verify that objects referenced by tags are of the correct type required by the RPC operation.
How to Resolve
To resolve RPC_S_INVALID_TAG, developers should:
- Correct Parameter Usage: Ensure all parameters passed to RPC operations are correctly formatted and validated.
- Adjust Operation Context: If necessary, adjust the context in which the RPC call is being made to ensure compatibility with expected tags.
- Restore Data: In cases where data corruption might be a factor, restore or revalidate the input data before retrying the operation.
Developer Notes
Developers should pay close attention to tag validation logic within their applications and ensure that all RPC operations are properly formatted. This can help prevent RPC_S_INVALID_TAG errors and improve overall application reliability.
Related Errors
- RPC_E_CALL_FAILED: Indicates a failure in the RPC call itself, which may be related to issues with tags but could also indicate other problems.
- RPC_X_BAD_STUB_DATA: Suggests that there is an issue with the stub data passed during the RPC operation, possibly including invalid tags.
FAQ
Q: What does RPC_S_INVALID_TAG mean?
A: It indicates that an unexpected or invalid tag was encountered in a Remote Procedure Call (RPC) operation.
Q: How can I prevent this error?
A: Ensure all parameters passed to RPC operations are correctly formatted and validated, particularly those containing tags.
Q: Is RPC_S_INVALID_TAG critical?
A: While not necessarily catastrophic, it can indicate issues with application logic or data integrity. Addressing it is recommended for maintaining system stability.
Summary
The RPC_S_INVALID_TAG error (1733) is a specific parameter validation issue in Remote Procedure Call operations. Developers should ensure proper tag usage and validate all parameters to prevent this error. By following the diagnostic and resolution guidance provided, developers can maintain robust application behavior and reliability.