diff --git a/tools/testrunner/base_runner.py b/tools/testrunner/base_runner.py
index d287750c84..54a9e61b16 100644
--- a/tools/testrunner/base_runner.py
+++ b/tools/testrunner/base_runner.py
@@ -117,7 +117,7 @@ SLOW_ARCHS = [
 
 
 ModeConfig = namedtuple(
-    'ModeConfig', 'label flags timeout_scalefactor status_mode execution_mode')
+    'ModeConfig', 'label flags timeout_scalefactor status_mode')
 
 DEBUG_FLAGS = ["--nohard-abort", "--enable-slow-asserts", "--verify-heap"]
 RELEASE_FLAGS = ["--nohard-abort"]
@@ -127,7 +127,6 @@ DEBUG_MODE = ModeConfig(
     flags=DEBUG_FLAGS,
     timeout_scalefactor=4,
     status_mode="debug",
-    execution_mode="debug",
 )
 
 RELEASE_MODE = ModeConfig(
@@ -135,7 +134,6 @@ RELEASE_MODE = ModeConfig(
     flags=RELEASE_FLAGS,
     timeout_scalefactor=1,
     status_mode="release",
-    execution_mode="release",
 )
 
 # Normal trybot release configuration. There, dchecks are always on which
@@ -146,7 +144,6 @@ TRY_RELEASE_MODE = ModeConfig(
     flags=RELEASE_FLAGS,
     timeout_scalefactor=4,
     status_mode="debug",
-    execution_mode="release",
 )
 
 PROGRESS_INDICATORS = {
@@ -761,13 +758,7 @@ class BaseTestRunner(object):
   def _create_progress_indicators(self, test_count, options):
     procs = [PROGRESS_INDICATORS[options.progress]()]
     if options.json_test_results:
-      # TODO(machenbach): Deprecate the execution mode. Previously it was meant
-      # to differentiate several records in the json output. But there is now
-      # only one record and the mode information is redundant.
-      procs.append(progress.JsonTestProgressIndicator(
-        self.framework_name,
-        self.build_config.arch,
-        self.mode_options.execution_mode))
+      procs.append(progress.JsonTestProgressIndicator(self.framework_name))
 
     for proc in procs:
       proc.configure(options)
diff --git a/tools/testrunner/standard_runner.py b/tools/testrunner/standard_runner.py
index fc828c7e0e..ff58391110 100755
--- a/tools/testrunner/standard_runner.py
+++ b/tools/testrunner/standard_runner.py
@@ -364,10 +364,8 @@ class StandardTestRunner(base_runner.BaseTestRunner):
       ]
 
     assert os.path.exists(options.json_test_results)
-    complete_results = []
     with open(options.json_test_results, "r") as f:
-      complete_results = json.loads(f.read())
-    output = complete_results[0]
+      output = json.load(f)
     lines = []
     for test in output['slowest_tests']:
       suffix = ''
diff --git a/tools/testrunner/testproc/progress.py b/tools/testrunner/testproc/progress.py
index eb96e5c354..9ff943a5c2 100644
--- a/tools/testrunner/testproc/progress.py
+++ b/tools/testrunner/testproc/progress.py
@@ -349,7 +349,7 @@ class MonochromeProgressIndicator(CompactProgressIndicator):
 
 
 class JsonTestProgressIndicator(ProgressIndicator):
-  def __init__(self, framework_name, arch, mode):
+  def __init__(self, framework_name):
     super(JsonTestProgressIndicator, self).__init__()
     # We want to drop stdout/err for all passed tests on the first try, but we
     # need to get outputs for all runs after the first one. To accommodate that,
@@ -358,8 +358,6 @@ class JsonTestProgressIndicator(ProgressIndicator):
     self._requirement = base.DROP_PASS_STDOUT
 
     self.framework_name = framework_name
-    self.arch = arch
-    self.mode = mode
     self.results = []
     self.duration_sum = 0
     self.test_count = 0
@@ -429,24 +427,16 @@ class JsonTestProgressIndicator(ProgressIndicator):
       }
 
   def finished(self):
-    complete_results = []
-    if os.path.exists(self.options.json_test_results):
-      with open(self.options.json_test_results, "r") as f:
-        # On bots we might start out with an empty file.
-        complete_results = json.loads(f.read() or "[]")
-
     duration_mean = None
     if self.test_count:
       duration_mean = self.duration_sum / self.test_count
 
-    complete_results.append({
-      "arch": self.arch,
-      "mode": self.mode,
+    result = {
       "results": self.results,
       "slowest_tests": self.tests.as_list(),
       "duration_mean": duration_mean,
       "test_total": self.test_count,
-    })
+    }
 
     with open(self.options.json_test_results, "w") as f:
-      f.write(json.dumps(complete_results))
+      json.dump(result, f)
diff --git a/tools/unittests/run_tests_test.py b/tools/unittests/run_tests_test.py
index 75fe2d15f4..4cd2bdefd5 100755
--- a/tools/unittests/run_tests_test.py
+++ b/tools/unittests/run_tests_test.py
@@ -246,7 +246,7 @@ class SystemTest(unittest.TestCase):
       self, expected_results_name, actual_json, basedir):
     # Check relevant properties of the json output.
     with open(actual_json) as f:
-      json_output = json.load(f)[0]
+      json_output = json.load(f)
 
     # Replace duration in actual output as it's non-deterministic. Also
     # replace the python executable prefix as it has a different absolute
diff --git a/tools/unittests/testdata/expected_test_results1.json b/tools/unittests/testdata/expected_test_results1.json
index 02d2d6c2c1..08ac623cd7 100644
--- a/tools/unittests/testdata/expected_test_results1.json
+++ b/tools/unittests/testdata/expected_test_results1.json
@@ -1,7 +1,5 @@
 {
-  "arch": "x64", 
   "duration_mean": 1, 
-  "mode": "release", 
   "results": [
     {
       "command": "/usr/bin/python out/build/d8_mocked.py --test strawberries --random-seed=123 --nohard-abort --testing-d8-test-runner", 
diff --git a/tools/unittests/testdata/expected_test_results2.json b/tools/unittests/testdata/expected_test_results2.json
index fb57aad48d..dc353f6875 100644
--- a/tools/unittests/testdata/expected_test_results2.json
+++ b/tools/unittests/testdata/expected_test_results2.json
@@ -1,7 +1,5 @@
 {
-  "arch": "x64", 
   "duration_mean": 1, 
-  "mode": "release", 
   "results": [
     {
       "command": "/usr/bin/python out/build/d8_mocked.py bananaflakes --random-seed=123 --nohard-abort --testing-d8-test-runner",