diff --git a/functions.php b/functions.php
index b8367c0..c0fee35 100644
--- a/functions.php
+++ b/functions.php
@@ -216,6 +216,12 @@ function trailingslashit( $str ) {
  * - Number of errors.
  * - Overall execution time.
  *
+ * When the XML data is missing, empty, unparseable, or carries no usable
+ * result counts, execution stops with an error instead of returning an
+ * empty or hollow result, because such a result is either rejected much
+ * later with a confusing error or displayed in a misleading way. See
+ * issue #311.
+ *
  * @param string $xml_string The JUnit XML data as a string. This should be
  * well-formed XML representing the results of test executions, typically
  * generated by testing frameworks compatible with JUnit reporting.
@@ -237,14 +243,41 @@ function trailingslashit( $str ) {
  */
 function process_junit_xml( $xml_string ) {
 	if ( empty( $xml_string ) ) {
-		return '';
-		return '';
+		error_message( 'junit.xml is missing or empty, so there are no test results to report. Aborting instead of reporting an empty result as a success. See https://github.com/WordPress/phpunit-test-runner/issues/311.' );
+	}
+
+	$previous_libxml_setting = libxml_use_internal_errors( true );
+	libxml_clear_errors();
+
+	$xml = simplexml_load_string( $xml_string );
+
+	$errors = libxml_get_errors();
+	libxml_clear_errors();
+	libxml_use_internal_errors( $previous_libxml_setting );
+
+	if ( false === $xml ) {
+		$detail = '';
+		if ( ! empty( $errors ) ) {
+			$first  = $errors[0];
+			$detail = ' First parser error: ' . trim( $first->message ) . ' at line ' . (int) $first->line . '.';
+		}
+		error_message( 'junit.xml could not be parsed as XML, so the test results are unreadable. Aborting instead of reporting an unreadable result as a success.' . $detail . ' See https://github.com/WordPress/phpunit-test-runner/issues/311.' );
 	}
 
-	$xml        = simplexml_load_string( $xml_string );
 	$xml_string = null;
-	$project    = $xml->testsuite;
-	$results    = array();
+
+	// PHPUnit wraps everything in <testsuites>, but a root <testsuite>
+	// element is also a legitimate JUnit shape from other producers.
+	$project = 'testsuite' === $xml->getName() ? $xml : $xml->testsuite;
+	$results = array();
+
+	if (
+		! isset( $project['tests'] ) || '' === (string) $project['tests'] ||
+		! isset( $project['failures'] ) || '' === (string) $project['failures'] ||
+		! isset( $project['errors'] ) || '' === (string) $project['errors']
+	) {
+		error_message( 'junit.xml parsed but contains no usable test result counts, so the test results are unusable. A result without failure and error counts would be displayed as a success. Aborting instead. See https://github.com/WordPress/phpunit-test-runner/issues/311.' );
+	}
 
 	$results = array(
 		'tests'    => (string) $project['tests'],
@@ -255,7 +288,7 @@ function process_junit_xml( $xml_string ) {
 
 	$results['testsuites'] = array();
 
-	$testsuites = $xml->xpath( '//testsuites//testsuite[ ( count( testcase ) > 0 ) and ( @errors > 0 or @failures > 0 ) ]' );
+	$testsuites = $xml->xpath( '//testsuite[ ( count( testcase ) > 0 ) and ( @errors > 0 or @failures > 0 ) ]' );
 	foreach ( $testsuites as $testsuite ) {
 		$result = array(
 			'name'     => (string) $testsuite['name'],
diff --git a/report.php b/report.php
index 764ec54..b45ee39 100644
--- a/report.php
+++ b/report.php
@@ -84,7 +84,14 @@
 
 // Process the junit.xml file.
 log_message( 'Processing and uploading junit.xml' );
-$xml     = file_get_contents( $runner_vars['WPT_PREPARE_DIR'] . '/junit.xml' );
+$junit_path = $runner_vars['WPT_PREPARE_DIR'] . '/junit.xml';
+if ( ! file_exists( $junit_path ) ) {
+	error_message( 'junit.xml was not found at ' . $junit_path . ', so there are no test results to report. Aborting instead of reporting an empty result as a success. See https://github.com/WordPress/phpunit-test-runner/issues/311.' );
+}
+if ( ! is_readable( $junit_path ) ) {
+	error_message( 'junit.xml exists at ' . $junit_path . ' but is not readable. Fix the file permissions and run the report again. See https://github.com/WordPress/phpunit-test-runner/issues/311.' );
+}
+$xml     = file_get_contents( $junit_path );
 $results = process_junit_xml( $xml );
 
 /*