--- a/testing/mozharness/scripts/web_platform_tests.py
+++ b/testing/mozharness/scripts/web_platform_tests.py
@@ -8,24 +8,26 @@ import copy
 import glob
 import json
 import os
 import sys
 
 # load modules from parent dir
 sys.path.insert(1, os.path.dirname(sys.path[0]))
 
+from mozharness.base.errors import BaseErrorList
 from mozharness.base.script import PreScriptAction
 from mozharness.base.vcs.vcsbase import MercurialScript
 from mozharness.mozilla.blob_upload import BlobUploadMixin, blobupload_config_options
 from mozharness.mozilla.testing.testbase import TestingMixin, testing_config_options, TOOLTOOL_PLATFORM_DIR
 from mozharness.mozilla.testing.codecoverage import (
     CodeCoverageMixin,
     code_coverage_config_options
 )
+from mozharness.mozilla.testing.errors import HarnessErrorList
 
 from mozharness.mozilla.structuredlog import StructuredOutputParser
 from mozharness.base.log import INFO
 
 class WebPlatformTest(TestingMixin, MercurialScript, BlobUploadMixin, CodeCoverageMixin):
     config_options = [
         [['--test-type'], {
             "action": "extend",
@@ -240,17 +242,18 @@ class WebPlatformTest(TestingMixin, Merc
         self.geckodriver_path = os.path.join(dirs['abs_work_dir'], "geckodriver")
 
     def run_tests(self):
         dirs = self.query_abs_dirs()
         cmd = self._query_cmd()
 
         parser = StructuredOutputParser(config=self.config,
                                         log_obj=self.log_obj,
-                                        log_compact=True)
+                                        log_compact=True,
+                                        error_list=BaseErrorList + HarnessErrorList)
 
         env = {'MINIDUMP_SAVE_PATH': dirs['abs_blob_upload_dir']}
         env['RUST_BACKTRACE'] = '1'
 
         if self.config['allow_software_gl_layers']:
             env['MOZ_LAYERS_ALLOW_SOFTWARE_GL'] = '1'
         if self.config['enable_webrender']:
             env['MOZ_WEBRENDER'] = '1'