Google colab file download failed to fetch error

Question

I used google colab to make a dictionary, dump it into a json file and download the file into my laptop by this code:

from google.colab import files
import json

dict = {'apple': 'fruit', 'mango': 'fruit', 'carrot': 'vegetable', 'brocoli': 'vegetable', 'cat': 'animal'}

with open('sampleDictionary.json', 'w') as f:
  json.dump(dict, f)

files.download('sampleDictionary.json')
f.close()

When I try to run this code, it gives this error:

MessageError                              Traceback (most recent call last)
<ipython-input-29-1251d71a0a36> in <module>()
      7   json.dump(dict, f)
      8 
----> 9 files.download('sampleDictionary.json')
     10 f.close()

/usr/local/lib/python3.6/dist-packages/google/colab/files.py in download(filename)
    176       'port': port,
    177       'path': _os.path.abspath(filename),
--> 178       'name': _os.path.basename(filename),
    179   })

/usr/local/lib/python3.6/dist-packages/google/colab/output/_js.py in eval_js(script, ignore_result)
     37   if ignore_result:
     38     return
---> 39   return _message.read_reply_from_input(request_id)
     40 
     41 

/usr/local/lib/python3.6/dist-packages/google/colab/_message.py in read_reply_from_input(message_id, timeout_sec)
    104         reply.get('colab_msg_id') == message_id):
    105       if 'error' in reply:
--> 106         raise MessageError(reply['error'])
    107       return reply.get('data', None)
    108 

MessageError: TypeError: Failed to fetch

Click here to see the screenshot of my code and the error

Please help me out

Answer 1

you need to enable third-party cookies but for now it only works for Chrome browser, open

chrome://settings/content/cookies

make sure the option for Block third-party cookies is disabled and click add button in Allow section then add

colab.research.google.com

Answer 2

I encountered the same problem (MessageError: TypeError: Failed to fetch) while using colab.

then, I split file operations into different code units in a colab notebook; I put file open, write, close in one code unit, and use files.download() in the subsequent code unit.

the problem is gone!

Answer 3

The problem is that the file is not finished being written by the time google attempts to "fetch" the file.
Simple solution:

with open('sampleDictionary.json', 'w') as f:
  json.dump(dict, f)
time.sleep(10)
files.download('sampleDictionary.json')

More complicated solution could be put a for loop with a try catch statement for files.download, and then put a sleep in the catch. Keep a max loop time in case the file is never completed.

Answer 4

After trying chrome cookies, tried except loop, nothing worked for me, so I changed the way that I get my files. I used google drive file stream, it was very easy and efficient:

from google.colab import drive
drive.mount('/content/drive')

it will ask you for authorization code, you can find it after visiting the corresponding url.

with open('/content/drive/My Drive/foo.txt', 'w') as f:
  f.write('Hello Google Drive!')
  #other instructions

drive.flush_and_unmount()