WARNING: Failed to export metrics. Server responded with HTTP status code 415

I’ve been trying to periodically send a value as a metric to dynatrace using an OtlpHttpMetricExporter with a PeriodicMetricReader.

However, I’ve been getting the same error over and over again: WARNING: Failed to export metrics. Server responded with HTTP status code 415. Error message: Unable to parse response body, HTTP status message: Unsupported Media Type.

On the other hand, using a OtlpGrpcMetricExporter instead returns: WARNING: Failed to export metrics. Server responded with HTTP status code 200. Error message: OK

Both these warnings come from io.opentelemetry.sdk.internal.ThrottlingLogger doLog

What am I doing wrong?

Code:

MetricExporter metricExporter = OtlpHttpMetricExporter.builder()
				.setEndpoint(Constants.DYNATRACE_ENDPOINT_M)
			        .addHeader(Constants.DYNATRACE_AUTH,Constants.DYNATRACE_TOKEN)
				.build();

SdkMeterProvider sdkMeterProvider = SdkMeterProvider.builder()
				.registerMetricReader(PeriodicMetricReader.builder(metricExporter).build())
				.build();	
		
OpenTelemetry openTelemetry = OpenTelemetrySdk.builder()
					.setMeterProvider(sdkMeterProvider)
					.buildAndRegisterGlobal();

Meter meter = openTelemetry.meterBuilder(Constants.INSTRUMENTATION_LIB)
				.setInstrumentationVersion(Constants.INSTRUMENTATION_VERSION)
				.build();

// Builds set of metric's attributes
Attributes attributes = getAttributes();
		
// Builds gauge meter to record metric
meter.gaugeBuilder(metricStorage.getId()) // sets metric label
			.buildWithCallback(measurement -> { 
			measurement.record(5.00, attributes); // sets metric value and attributes
			});