This error has been going away for us when adding a /flash/pybytes_config.json file containing {"pybytes_autostart": false} in order to turn off Pybytes, see also Firmware Release v1.20.1 | Pycom user forum.
When adding an appropriate pybytes_config.json file, the boot process will display these messages:
Pybytes configuration read from /flash/pybytes_config.json
Not starting Pybytes as auto-start is disabled
You can read more about the pybytes_config.json at