I've tried WiFiManager with with MicroPython builds:

tinypico-idf3-20191220-v1.12
tinypico-idf3-20200223-v1.12-195-gb16990425

I'm just running the bare main.py included in WiFiManager-master.

The traceback occurs write after the SSID and password check succeeds. The wifi.dat is not saved.

Errors:
Connected. Network config: ('192.168.4.89', '255.255.255.0', '192.168.4.254', '192.168.4.254')
Traceback (most recent call last):
File "main.py", line 4, in
File "wifimgr.py", line 60, in get_connection
File "wifimgr.py", line 306, in start
File "wifimgr.py", line 213, in handle_configure
File "wifimgr.py", line 112, in send_response
File "wifimgr.py", line 103, in send_header
OSError: [Errno 5] EIO

I was able to get the code to "work" by wrapping the send_header and send_response functions with try and except. I think the cause may be that the client connection is getting disconnected when the just entered network credentials are tested.

Any help is appreciated!
Thanks!