Robotframework "Choose file" causes AttributeError: module 'base64' has no attribute 'encodestring' in docker

Question

I'm trying to run a test in a docker container, which runs locally with no issues: I want to upload a correct.csv file from 'correct' directory

*** Keyword ***
Upload file
    [Arguments]    ${directory}    ${file}
    Choose File    ${choose_file_input}    ${EXECDIR}/Files/${directory}/${file}

** Test case ***
Upload
    Upload file    correct    correct.csv

But when running test in docker I get a FAIL with the AttributeError: module 'base64' has no attribute 'encodestring'. Is it because there is no GUI in docker? or the encoding needs to be fixed? Or eventually maybe there is another solution I can use for uploading files?

15:20:01.250    INFO    Sending /App/Files/correct/correct.csv to browser.  
15:20:01.251    DEBUG   POST http://192.168.1.29:4444/wd/hub/session/4b6d453b394adaaa51bb4149e9ba8678/elements {"using": "xpath", "value": "//div[@id=\"upload\"]//input"}  
15:20:01.252    DEBUG   Starting new HTTP connection (1): 192.168.1.29:4444 
15:20:01.305    DEBUG   http://192.168.1.29:4444 "POST /wd/hub/session/4b6d453b394adaaa51bb4149e9ba8678/elements HTTP/1.1" 200 90   
15:20:01.305    DEBUG   Finished Request    
15:20:01.618    FAIL    AttributeError: module 'base64' has no attribute 'encodestring' 
15:20:01.619    DEBUG   Traceback (most recent call last):
  File "/usr/local/lib/python3.9/site-packages/SeleniumLibrary/__init__.py", line 490, in run_keyword
    return DynamicCore.run_keyword(self, name, args, kwargs)
  File "/usr/local/lib/python3.9/site-packages/robotlibcore.py", line 103, in run_keyword
    return self.keywords[name](*args, **(kwargs or {}))
  File "/usr/local/lib/python3.9/site-packages/SeleniumLibrary/keywords/formelement.py", line 224, in choose_file
    self.find_element(locator).send_keys(file_path)
  File "/usr/local/lib/python3.9/site-packages/selenium/webdriver/remote/webelement.py", line 475, in send_keys
    value = self._upload(local_file)
  File "/usr/local/lib/python3.9/site-packages/selenium/webdriver/remote/webelement.py", line 695, in _upload
    content = base64.encodestring(fp.getvalue())

Answer 1

We were running into this issue as well, but going back to an older version of Python was not an option due to incompatibilities with other libraries. If you find yourself in the same spot, you can re-create the alias like so:

import base64
base64.encodestring = base64.encodebytes

In whatever your entry-point is.