macOS kernel return 0xE0004043 (kIOUSBInvalidSSEndpoint): meaning

Status / error code:		Category:

Constant name:
Source:		Operating System:
Description: A SuperSpeed endpoint descriptor set is invalid or incomplete.

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kIOUSBTooManyTransactionsPending	kIOUSBStreamsNotSupported

kIOUSBInvalidSSEndpoint

SuperSpeed endpoint descriptors are a set

kIOUSBInvalidSSEndpoint is raised by the macOS USB stack when it cannot accept an endpoint declared by a SuperSpeed device. The definition in IOKit/usb/USB.h specifically calls out a missing Endpoint Companion Descriptor as the usual cause. For SuperSpeed, the endpoint description is not limited to the ordinary endpoint descriptor: the companion descriptor carries transport parameters used to configure the endpoint.

This is therefore a descriptor or configuration problem, not a generic transfer failure. It differs from kIOUSBEndpointCountExceeded, where a valid endpoint cannot be created because the controller has reached a limit, and from kIOUSBStreamsNotSupported, where the endpoint is valid but the host controller lacks a requested capability.

What to inspect

Capture the complete configuration-descriptor tree from the device, including the active configuration, interface number, alternate setting, endpoint descriptor, and the descriptor immediately following it.
Check descriptor ordering, lengths, endpoint address, transfer type, and the SuperSpeed companion data rather than inspecting only the endpoint number reported by an application.
Record the negotiated bus speed and the controller path. A device that exposes different configurations or alternate settings can make the failure appear only on one path.
Correct the device firmware or descriptor generator. Retrying the same request cannot make an invalid descriptor chain valid.

References

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