It is likely because the file is open elsewhere. Windows is very strict on file access. 


https://build.chromium.org/p/chromium.perf/builders/Win%2010%20High-DPI%20Perf%20%285%29/builds/109/steps/battor.tough_video_cases/logs/stdio


CRITICAL:root:Finding return code for BattOr shell.
CRITICAL:root:Found return code: None
INFO:root:Uploading c:\users\chrome~1.lab\appdata\local\temp\tmpdbwlnt to gs://chrome-telemetry-output/battor-serial-log-2016-09-25_15-04.txt-7011.txt
WARNING:root:Cannot dump browser state: No browser.
WARNING:root:Either tab has crashed or browser does not support taking tab screenshot. Skip taking screenshot on failure.
Traceback (most recent call last):
  File "C:\b\c\b\Win_10_High_DPI_Perf__5_\src\third_party\catapult\telemetry\telemetry\internal\story_runner.py", line 78, in _RunStoryAndProcessErrorIfNeeded
    test.WillRunStory(state.platform)
  File "C:\b\c\b\Win_10_High_DPI_Perf__5_\src\third_party\catapult\telemetry\telemetry\web_perf\timeline_based_measurement.py", line 282, in WillRunStory
    platform.tracing_controller.StartTracing(self._tbm_options.config)
  File "C:\b\c\b\Win_10_High_DPI_Perf__5_\src\third_party\catapult\telemetry\telemetry\core\tracing_controller.py", line 43, in StartTracing
    self._tracing_controller_backend.StartTracing(tracing_config, timeout)
  File "C:\b\c\b\Win_10_High_DPI_Perf__5_\src\third_party\catapult\telemetry\telemetry\internal\platform\tracing_controller_backend.py", line 91, in StartTracing
    if agent.StartAgentTracing(config, timeout):
  File "C:\b\c\b\Win_10_High_DPI_Perf__5_\src\third_party\catapult\telemetry\telemetry\internal\platform\tracing_agent\battor_tracing_agent.py", line 73, in StartAgentTracing
    self._battor.StartTracing()
  File "C:\b\c\b\Win_10_High_DPI_Perf__5_\src\third_party\catapult\common\battor\battor\battor_wrapper.py", line 155, in StartTracing
    self._SendBattorCommand(self._START_TRACING_CMD)
  File "C:\b\c\b\Win_10_High_DPI_Perf__5_\src\third_party\catapult\common\battor\battor\battor_wrapper.py", line 265, in _SendBattorCommand
    self._UploadSerialLogToCloudStorage()
  File "C:\b\c\b\Win_10_High_DPI_Perf__5_\src\third_party\catapult\common\battor\battor\battor_wrapper.py", line 288, in _UploadSerialLogToCloudStorage
    self._serial_log_bucket, remote_path, self._serial_log_file.name)
  File "C:\b\c\b\Win_10_High_DPI_Perf__5_\src\third_party\catapult\common\py_utils\py_utils\cloud_storage.py", line 315, in Insert
    _RunCommand(command_and_args)
  File "C:\b\c\b\Win_10_High_DPI_Perf__5_\src\third_party\catapult\common\py_utils\py_utils\cloud_storage.py", line 160, in _RunCommand
    raise CloudStorageError(stderr)
CloudStorageError: CommandException: Error opening file "file://c:\users\chrome~1.lab\appdata\local\temp\tmpdbwlnt": .