Google colab file download failed to fetch error

问题

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

回答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

回答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!

回答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.

回答4:

It did not worked for me too. One way is to not use the

files.download(filename)

and simply going to the Files section and there will be your file. Right click and download it.

There is a > on the left of google colab editor and click it and there will be Table of Contents, Code Snippets and Files section.

回答5:

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

f.close()
drive.flush_and_unmount()

来源：https://stackoverflow.com/questions/53581023/google-colab-file-download-failed-to-fetch-error