microg/GmsCore · error · IllegalStateException

dataType must be set

Error message

dataType must be set

What it means

Thrown by DataSource.Builder.build() when no DataType has been set. A DataSource must declare what kind of data it produces (e.g. TYPE_STEP_COUNT_DELTA); without a DataType the resulting DataSource would be invalid, so the builder refuses to construct it.

Source

Thrown at play-services-fitness/src/main/java/com/google/android/gms/fitness/data/DataSource.java:199

    /**
     * A builder that can be used to construct new data source objects. In general, a built data source should be saved in memory to avoid the cost
     * of re-constructing it for every request.
     */
    public static class Builder {
        private DataType dataType;
        private Device device;
        private Application application;
        private int type = -1;
        private String streamName = "";

        /**
         * Finishes building the data source and returns a DataSource object.
         *
         * @throws IllegalStateException If the builder didn't have enough data to build a valid data source.
         */
        @NonNull
        public DataSource build() {
            if (dataType == null) throw new IllegalStateException("dataType must be set");
            if (type < 0) throw new IllegalStateException("type must be set");
            return new DataSource(dataType, type, device, application, streamName);
        }

        /**
         * Sets the package name for the application that is recording or computing the data. Used for data sources that aren't built into the platform
         * (local sensors and BLE sensors are built-in). It can be used to identify the data source, to disambiguate between data from different
         * applications, and also to link back to the original application for a detailed view.
         */
        @NonNull
        public Builder setAppPackageName(@NonNull String packageName) {
            Application application = Application.GMS_APP;
            this.application = Constants.GMS_PACKAGE_NAME.equals(packageName) ? Application.GMS_APP : new Application(packageName);
            return this;
        }

        /**
         * Sets the package name for the application that is recording or computing the data based on the app's context. This method should be

View on GitHub (pinned to 157c9d86ac)

Solutions

1. Call setDataType(DataType.AGGREGATE_...) or the appropriate DataType before build().
2. If the data type is dynamic, assert/validate it is non-null before building.
3. Wrap the dataType in an Optional and throw a clear app-level error early if missing.
4. Check that you are building the intended Builder instance (not a fresh one that lost the setDataType call).

Example fix

// before
DataSource src = new DataSource.Builder()
    .setType(DataSource.TYPE_RAW)
    .build(); // throws
// after
DataSource src = new DataSource.Builder()
    .setDataType(DataType.TYPE_STEP_COUNT_DELTA)
    .setType(DataSource.TYPE_RAW)
    .build();

if (builderDataType == null) throw new IllegalStateException("setDataType must be called before build()");

boolean sourceReady(DataSource.Builder b, DataType dt) { return dt != null; }

try { src = dataSourceBuilder.build(); } catch (IllegalStateException e) { throw new ConfigException("DataSource missing dataType", e); }

When it happens

Trigger: Calling DataSource.Builder.build() without ever calling setDataType(DataType) on that builder.

Common situations: Copy-pasted builder code where the setDataType line was deleted; conditional config where the data type comes from a null variable; refactors that split builder construction across methods and skip the dataType step.

Understand the failure class

Background: "missing required argument" and "the following required arguments were not provided": what required-argument errors mean and how to fix them — this error's family across 20 libraries.

Related errors

• type must be set
• deleteAll=true but keys are provided
• Missing required properties: token
• Missing required properties: scopes
• Missing required properties: account

AI-assisted analysis of microg/GmsCore@157c9d86ac (2026-09-06). Data as JSON: /api/errors/f9cd1ccecb551093. Report an issue: GitHub.