microg/GmsCore · error · UnsupportedAttestationConveyancePreferenceException

Attestation conveyance preference ${attachment} not supporte

Error message

Attestation conveyance preference ${attachment} not supported

What it means

AttestationConveyancePreference.fromString() maps an attestation conveyance string ("none", "indirect", "direct", "enterprise") to the enum. Unrecognized values throw UnsupportedAttestationConveyancePreferenceException so bad attestation settings fail fast rather than being ignored.

Source

Thrown at play-services-fido/src/main/java/com/google/android/gms/fido/fido2/api/common/AttestationConveyancePreference.java:52

    }

    @Override
    public int describeContents() {
        return 0;
    }

    @Override
    public void writeToParcel(Parcel dest, int flags) {
        dest.writeString(toString());
    }

    @Hide
    @NonNull
    public static AttestationConveyancePreference fromString(String attachment) throws UnsupportedAttestationConveyancePreferenceException {
        for (AttestationConveyancePreference value : values()) {
            if (value.value.equals(attachment)) return value;
        }
        throw new UnsupportedAttestationConveyancePreferenceException("Attestation conveyance preference " + attachment + " not supported");
    }

    public static Creator<AttestationConveyancePreference> CREATOR = new Creator<AttestationConveyancePreference>() {
        @Override
        public AttestationConveyancePreference createFromParcel(Parcel source) {
            try {
                return AttestationConveyancePreference.fromString(source.readString());
            } catch (UnsupportedAttestationConveyancePreferenceException e) {
                throw new RuntimeException(e);
            }
        }

        @Override
        public AttestationConveyancePreference[] newArray(int size) {
            return new AttestationConveyancePreference[size];
        }
    };

View on GitHub (pinned to 157c9d86ac)

Solutions

Use one of the supported strings exactly: "none", "indirect", "direct" (or "enterprise" if the enum defines it).
Prefer the enum constants directly instead of parsing strings.
Update the microG FIDO library if a newer preference value must be accepted.

Example fix

// before
var pref = AttestationConveyancePreference.fromString("attestation-direct");
// after
var pref = AttestationConveyancePreference.fromString("direct");

Defensive patterns

Strategy: validation

Validate before calling

boolean valid = java.util.Arrays.stream(AttestationConveyancePreference.values()).anyMatch(p -> p.toString().equals(preference));
if (!valid) preference = "none";

Try / catch

try { pref = AttestationConveyancePreference.fromString(value); } catch (UnsupportedAttestationConveyancePreferenceException e) { pref = AttestationConveyancePreference.fromString("none"); }

Prevention

Whitelist the accepted strings ("none", "indirect", "direct") before parsing.
Default to "none" when the server value is unknown — attestation is optional.
Use enum constants when constructing PublicKeyCredentialCreationOptions directly.

When it happens

Trigger: Calling fromString with a value outside the enum, e.g. a typo like "attestation-direct", the empty string, or a newer spec value not present in this library version. (The message text mistakenly says 'attachment' — it refers to the conveyance preference.)

Common situations: Server-issued WebAuthn options containing attestation values from a newer spec than the embedded library supports; hand-written option JSON in tests with case errors ("Direct").

Understand the failure class

Background: Invalid enum value errors: "Unknown type", "Invalid scope", "must be one of" — when a string is not on the library's allowed list — this error's family across 23 libraries.

Related errors

AI-assisted analysis of microg/GmsCore@157c9d86ac (2026-09-06). Data as JSON: /api/errors/54a9c8665ab1a12c. Report an issue: GitHub.