What does Windows error code 1744 (RPC_S_PROTSEQ_NOT_FOUND) mean?

 
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RPC_S_STRING_TOO_LONG RPC_S_PROCNUM_OUT_OF_RANGE

RPC_S_PROTSEQ_NOT_FOUND

Protocol sequence names identify concrete RPC transport stacks

RPC_S_PROTSEQ_NOT_FOUND means the requested protocol sequence could not be located for the operation. Examples of protocol-sequence strings include ncacn_ip_tcp, ncacn_np, and ncalrpc. They are not generic names such as tcp or pipe.

This differs from RPC_S_PROTSEQ_NOT_SUPPORTED: a sequence may be a valid RPC concept but not present in the current binding vector or lookup context, while a support error says the runtime or operating system cannot use it.

What to inspect

  • Preserve the exact protocol-sequence string, including spelling and underscores.
  • Enumerate server bindings and protocol sequences instead of assuming a transport was successfully registered.
  • When selecting a binding from a vector, compare the parsed protocol-sequence component rather than searching the full string binding with substring logic.
  • Check startup errors from RpcServerUseProtseq* before later code searches for that sequence.

The failure is about RPC transport selection. DNS and application procedure dispatch happen at different stages.

References


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