11. errno

The errno module in MicroPython provides access to symbolic error codes for OSError exceptions.

These error codes are useful for handling specific error conditions in your code.

11.1. Error codes

The code below uses the REPL to print the dictionary of error codes.

from microbit import *
import errno

# print(help(errno))
print(errno.errorcode)

errorcode -- {1: 'EPERM', 2: 'ENOENT', 5: 'EIO',
9: 'EBADF', 11: 'EAGAIN', 12: 'ENOMEM',
13: 'EACCES', 17: 'EEXIST', 19: 'ENODEV',
21: 'EISDIR', 22: 'EINVAL', 95: 'EOPNOTSUPP',
98: 'EADDRINUSE', 103: 'ECONNABORTED',
104: 'ECONNRESET', 105: 'ENOBUFS',
107: 'ENOTCONN', 110: 'ETIMEDOUT',
111: 'ECONNREFUSED', 113: 'EHOSTUNREACH',
114: 'EALREADY', 115: 'EINPROGRESS'}

---

11.2. File open error

The code below uses the REPL to print the output.

# Imports go at the top
from microbit import *
import errno

try:
    with open('non_existent_file.txt', 'r') as file:
        content = file.read()
except OSError as e:
    if e.errno == errno.ENOENT:
        print("Error: File not found.")
    else:
        print("Error: {}".format(e))

---

11.3. Error code meanings

See: https://docs.python.org/3.12/library/errno.html#module-errno

Here are the meanings of each error code in the provided list:

1. EPERM (1): Operation not permitted.

2. ENOENT (2): No such file or directory.

3. EIO (5): Input/output error.

4. EBADF (9): Bad file descriptor.

5. EAGAIN (11): Try again (resource temporarily unavailable).

6. ENOMEM (12): Out of memory.

7. EACCES (13): Permission denied.

8. EEXIST (17): File exists.

9. ENODEV (19): No such device.

10. EISDIR (21): Is a directory.

11. EINVAL (22): Invalid argument.

12. EOPNOTSUPP (95): Operation not supported.

13. EADDRINUSE (98): Address already in use.

14. ECONNABORTED (103): Software caused connection abort.

15. ECONNRESET (104): Connection reset by peer.

16. ENOBUFS (105): No buffer space available.

17. ENOTCONN (107): Transport endpoint is not connected.

18. ETIMEDOUT (110): Connection timed out.

19. ECONNREFUSED (111): Connection refused.

20. EHOSTUNREACH (113): No route to host.

21. EALREADY (114): Operation already in progress.

22. EINPROGRESS (115): Operation now in progress.