Error 28

[jubenjum]

Trying to write into a file in my wipy 3.0 I get the following error output:

>OKUnhandled exception in callback handler
Traceback (most recent call last):
  File "<stdin>", line 39, in _handler
  File "<stdin>", line 45, in write_to_file
OSError: 28

Anyhow I don't have any big file in the flash and it should enougth space to save the file on it, do you know what can I do? maybe by doing a factory reset will solve this problem?

Thanks for your ideas