microg/GmsCore · error · IllegalStateException

Value is not a string.

Error message

Value is not a string.

What it means

Format guard in fitness Value.asString: the Value's format is not FORMAT_STRING, so the internal stringValue cannot be returned. It fires when a numeric- or map-formatted Value is read through the string accessor.

Source

Thrown at play-services-fitness/src/main/java/com/google/android/gms/fitness/data/Value.java:107

    /**
     * Returns the value of this object as a int.
     *
     * @throws IllegalStateException If this {@link Value} does not correspond to a {@link com.google.android.gms.fitness.data.Field#FORMAT_INT32}
     */
    public int asInt() {
        if (format != FORMAT_INT32) throw new IllegalStateException("Value is not a int.");
        return Float.floatToRawIntBits(this.value);
    }

    /**
     * Returns the value of this object as a string.
     *
     * @throws IllegalStateException If this {@link Value} does not correspond to a {@link com.google.android.gms.fitness.data.Field#FORMAT_STRING}
     */
    @NonNull
    public String asString() {
        if (format != FORMAT_STRING) throw new IllegalStateException("Value is not a string.");
        if (stringValue == null) return "";
        return stringValue;
    }

    /**
     * Clears any value currently associated with the given {@code key} in the map. This method can be used only on map values.
     *
     * @param key The key you're modifying.
     * @deprecated Use {@link DataPoint.Builder} to construct new {@link DataPoint} instances.
     */
    @Deprecated
    public void clearKey(String key) {
        if (format != FORMAT_MAP) throw new IllegalStateException("Value is not a map.");
        if (mapValue != null) {
            mapValue.remove(key);
        }
    }

View on GitHub (pinned to 157c9d86ac)

Solutions

1. Check getFormat() == Field.FORMAT_STRING before calling asString()
2. Use the accessor matching the Value's actual format

When it happens

Trigger: Thrown at play-services-fitness/src/main/java/com/google/android/gms/fitness/data/Value.java:107 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of microg/GmsCore@157c9d86ac (2026-09-06). Data as JSON: /api/errors/933e44407cad64a9. Report an issue: GitHub.