Singpass FAPI 2.0 Error Troubleshooting Guide – Partner Support Center

Status Code	error	error_description	Common Causes	What To Do
400	`bad_request`	`Request parameters invalid`	`Missing/invalid parameters` `authentication_context_message invalid` Contains special characters No DPoP header	Check full POST body Must match ^[a-zA-Z0-9 ]*$ (only letters, numbers, spaces)
400	`invalid_scope`	`Scope not registered`	Scope not onboarded in SDP	Verify scope in developer portal
400	`invalid_request`	`An error has occurred.`	Missing DPoP header / wrong content type Client doesnt allow ACR values please remove the ACR	Ensure DPoP header present and content-type is application/x-www-form-urlencoded
400	`invalid_client`	`RP failed client assertion authentication`	Wrong signing key / expired JWT	Check client assertion claims and signature
401	`invalid_dpop_proof`	`Failed to verify the DPoP proof JWT`	Expired / wrong htm / wrong htu	Check DPoP Ensure exp ≤120s, htm=POST, htu exact match
502	`upstream_dependency_error`	`An error has occurred.`	JWKS not reachable	Check JWKS endpoint Ensure public HTTPS access and valid JSON

Error Code	What It Means	Common Causes	What To Do
PX-E0013	request_uri missing/expired/mismatch	Expired PAR / wrong client_id	Ensure request_uri from latest PAR response
PX-E1000	Request parameters invalid.	not state/request_uri parameter	check if paramenters are correct
PX-E0008	Scope(s) provided may be unregistered

Status Code	Error	error_description	Common Causes	What To Do
400	invalid_grant	`Authorization code invalid`	Code reused / expired / redirect_uri mismatch	Use fresh code, check redirect_uri check post request parameters
400	invalid_request	`An error has occurred.`	Missing parameters	Check full POST body
400	invalid_client	`RP failed client assertion authentication`	Wrong signing key / expired JWT	Check client assertion claims and signature
401	`invalid_dpop_proof`	`Failed to verify the DPoP proof JWT`	Expired / wrong htm / wrong htu	Check DPoP Ensure exp ≤120s, htm=POST, htu exact match
401	`invalid_dpop_proof`	`Incoming DPOP Proof JWT does not match the initial dpop_jkt sent at PAR endpoint`	Different key from PAR	Use same DPoP keypair throughout flow

Status Code	Error	error_desciption	What To Do

Status Code	Error	error_desciption	What To Do
400	`invalid_request`	`Myinfo profile not provisioned`	Use test user with provisioned Myinfo profile
401	`invalid_dpop_proof`	`DPoP verification failed`	Ensure correct DPoP key + exp ≤120s

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