Dear All,

I conducted an experiment on oTree around 3 years ago. I have recently started working on updating the experiment, but I am experiencing technical difficulties running it. I could run it locally, but when I tried to upload it on Heroku, it said:

Build output
-----> Building on the Heroku-22 stack
-----> Using buildpack: heroku/python
-----> Python app detected
-----> Using Python version specified in runtime.txt
 !     Requested runtime 'python-3.7.9' is not available for this stack (heroku-22).
 !     For supported versions, see: https://devcenter.heroku.com/articles/python-support
 !     Push rejected, failed to compile Python app.

 !     Push failed
oTree Hub Advice
        You can fix this error by upgrading oTree.
        Or, if you need to use an older oTree version, 
        then install the Heroku CLI and run this command: "heroku stack:set heroku-20 --app YOUR-SITE-NAME"

After that I typed this error in google and I was redirected to: https://devcenter.heroku.com/articles/python-support#supported-runtimes. From there I followed the directions in the last section called "Checking the Python Buildpack Version". Then, I cleared the current buildpacks and added the recommended buildpacks. Then, I deployed the experiment again and get the same error. I cannot get out of this vicious cycle. 

I have the feeling that the issue is related to me using an older version of otree which requires an older version of Pycharm. Is there a way to update both simultaneously without having to download a newer version of both and coding the experiment again? 

I would appreciate any feedback! 

Thanks in advance!

it looks like that heroku deployment does not support older python versions anymore. If you need run python 3.7, you should find a way to specify the Heroku-20 stack

Can you past the content of your requirement text?

I already fixed it (somehow managed to specify the Heroku-20 stack). Otherwise, here is the requirement text: 

# oTree-may-overwrite-this-file
# IF YOU MODIFY THIS FILE, remove these comments. 
# otherwise, oTree will automatically overwrite it.
otree>=3.4.0,<5
psycopg2>=2.8,<2.9
sentry-sdk==0.7.9

Thanks!