ERROR_DEVICE_IN_USE - 2404 (0x964)
The device is in use by an active process and cannot be disconnected.
Updated: Feb 21, 2026
Technical Background
The error code ERROR_DEVICE_IN_USE (2404, 0x964) is a specific Windows API error that indicates an attempt to disconnect or release a device object while it is still in use by one or more active processes. This error typically arises when the system detects that there are ongoing operations or resources associated with the device.
Error Details
The ERROR_DEVICE_IN_USE error code signifies that the device cannot be safely disconnected because it is currently being utilized by an active process. This can occur in various scenarios, such as during a file operation, device driver interaction, or system resource management tasks.
Common Causes
- Active Processes: The device is still in use by one or more processes that are actively performing operations on the device.
- File Operations: An attempt to close an open handle to a device while it is being accessed by another process.
- Driver Interactions: A driver or system component is currently using the device for data transfer, configuration, or other critical tasks.
Real-World Context
This error can occur in various applications and scenarios where devices are managed dynamically. For example, when a user attempts to eject a USB drive while it is being read by an application, or when a network adapter is still in use by a network connection or service.
Is This Error Critical?
The criticality of this error depends on the context in which it occurs. If the device is not required for immediate operations, the system may provide alternative methods to safely terminate processes using the device. However, if the operation is critical and cannot be delayed, the error may necessitate a more forceful disconnection or termination.
How to Diagnose
- Review Operation Context: Determine which process is currently using the device by examining the active processes in the system.
- Validate Parameters: Ensure that all parameters passed to the API calls are correct and valid.
- Confirm Object Types: Verify that the object types being manipulated are consistent with expected behavior.
How to Resolve
- Correct Parameter Usage: Ensure that any parameters related to device operations are correctly set.
- Adjust Operation Context: If possible, adjust the operation context to avoid conflicts or ensure that all processes using the device have completed their tasks.
- Restore Data: In cases where data integrity is compromised due to the error, restore the data if possible.
Developer Notes
Developers should handle this error by providing appropriate feedback to users and ensuring that operations are retried with correct parameters. Additionally, applications should be designed to gracefully handle device disconnection scenarios to avoid system instability or data corruption.
Related Errors
FAQ
Q: Can this error occur on any type of device?
A: Yes, it can occur with any type of device that is in use by an active process.
Q: How can I prevent this error from occurring?
A: Ensure that all operations related to the device are completed before attempting to disconnect or release it. Use appropriate synchronization mechanisms to manage access to shared resources.
Summary
The ERROR_DEVICE_IN_USE (2404, 0x964) is a specific Windows API error indicating that an attempt to disconnect a device has failed because the device is in use by one or more active processes. Developers should handle this error gracefully and ensure that operations are managed correctly to avoid data corruption or system instability.