Missing environment variable CS50_TOKEN

[petehoch]

🏷️ Discussion Type

Question

Body

How on Earth do I set this up? I have tried from scratch twice and I can not run the test on my deep.py file. At least my code was not deleted. But I am out of thoughts here.

[asametduran]

Hi @petehoch,

This error indicates that your Codespace environment is missing the authorization token required by CS50 tools (such as check50 or submit50) to verify your identity.

Here are the most reliable steps to resolve it without losing your work:

1. Launch via the Official CS50 Portal

If you created this Codespace directly through github.com/codespaces or a regular GitHub repository, the required CS50 environment variables will not be injected.

• Always access your development environment through cs50.dev.
• Launching from cs50.dev automatically authenticates your session and injects the $CS50_TOKEN.

---

2. Update and Re-authenticate the CS50 CLI

Run the following command in your Codespace terminal:

update50

Wait for the script to finish and follow any prompts or authorization links printed to the terminal.

3. Re-authorize CS50 in GitHub Settings

If your token has expired or permissions were interrupted:

1. Go to your personal GitHub settings: Settings > Applications > Authorized OAuth Apps.
2. Locate CS50 (or submit50) and revoke its access.
3. Return to your Codespace terminal and re-run your check50 command on deep.py.
4. It will provide a new URL to authorize your account.

---

4. Rebuild the Container

If the token remains missing, reinitializing the dev container configuration will restore the environment variables:

1. Press Ctrl + Shift + P (or Cmd + Shift + P on macOS) to open the Command Palette.
2. Select Codespaces: Rebuild Container.

Note: Rebuilding the container will safely keep all your workspace files intact (including deep.py), but it will refresh the container runtime and environment configurations.

[ps2builds]

Environment level vs repo level secrets got me once too, took an embarrassing hour to spot. The workflow logs usually hint at it with an empty variable warning right at the failing step. If that's clean, check for a trailing space from pasting, that's bitten me more than once. Also make sure the secret name in the YAML matches exactly, case and all. What does the failing step's log show?

[malkamanuranga]

Hey @petehoch, don't panic, your deep.py code is totally safe!

Just a quick heads-up: the advice from @ps2builds is meant for regular GitHub Actions pipelines. Since you are doing the CS50 course, don't drive yourself crazy looking for YAML files or repository secrets—you don't need to mess with any of that.

@asametduran nailed the exact fix. 99% of the time, this specific error happens because you opened your Codespace directly from your normal GitHub dashboard instead of the official CS50 portal.

Here is the absolute quickest way to get it working again:

Close the Codespace tab you currently have open.

Go directly to cs50.dev in your browser.

Log in with your GitHub account from there. (Opening it through this specific website is what magically generates that missing CS50_TOKEN and passes it to your workspace).

Once it loads, try running your check50 command on your deep.py file again.

If it still gives you trouble, just type update50 in the terminal, hit enter, and let it run. Good luck with the assignment!

[idrivehtbusiness]

I wouldn't create a new CS50_TOKEN manually just yet. The current CS50 documentation says that check50 and submit50 should work in the official CS50 environment without configuring a personal access token.

Here's what I'd check first:

1. Open https://cs50.dev/ and make sure you're using the official CS50 Codespace, rather than a regular GitHub Codespace.
2. Sign in at https://submit.cs50.io/ with the same GitHub account and complete the authorization if prompted.
3. Go back to your Codespace and restart it. Keep your existing files; there's no need to delete the environment.
4. Open the folder containing deep.py and try the exact command from the assignment:

check50 cs50/problems/2022/python/deep

If it still reports a missing token, check whether the authentication variables exist without printing their values:

test -n "${CS50_TOKEN:-}" && echo "CS50_TOKEN set" || echo "CS50_TOKEN missing"
test -n "${GITHUB_TOKEN:-}" && echo "GITHUB_TOKEN set" || echo "GITHUB_TOKEN missing"

GITHUB_TOKEN is normally provided in standard GitHub Codespaces, but CS50_TOKEN is not a standard GitHub environment variable. Don't paste either token publicly or put it directly into your code.

If you're using a regular Codespace instead of cs50.dev, that distinction may explain why the expected CS50 authentication setup isn't available.

Could you share the exact error from check50 and confirm whether you're working at cs50.dev or in a Codespace created directly from GitHub? That would help determine whether this is an authentication issue or something else.

[petehoch]

Thanks for all of the follow up. I restarted from the beginning of the course page and on the third relaunch of everything it started to work. Just finished week0 & week1 and everything looks good. Seems that turning it off and back on again does work! Thanks, Pete

…

On Oct 9, 2026, at 6:39 AM, Jules Charly ***@***.***> wrote: I wouldn't create a new CS50_TOKEN manually just yet. The current CS50 documentation says that check50 and submit50 should work in the official CS50 environment without configuring a personal access token. Here's what I'd check first: Open https://cs50.dev/ and make sure you're using the official CS50 Codespace, rather than a regular GitHub Codespace. Sign in at https://submit.cs50.io/ with the same GitHub account and complete the authorization if prompted. Go back to your Codespace and restart it. Keep your existing files; there's no need to delete the environment. Open the folder containing deep.py and try the exact command from the assignment: check50 cs50/problems/2022/python/deep If it still reports a missing token, check whether the authentication variables exist without printing their values: test -n "${CS50_TOKEN:-}" && echo "CS50_TOKEN set" || echo "CS50_TOKEN missing" test -n "${GITHUB_TOKEN:-}" && echo "GITHUB_TOKEN set" || echo "GITHUB_TOKEN missing" GITHUB_TOKEN is normally provided in standard GitHub Codespaces, but CS50_TOKEN is not a standard GitHub environment variable. Don't paste either token publicly or put it directly into your code. If you're using a regular Codespace instead of cs50.dev, that distinction may explain why the expected CS50 authentication setup isn't available. Could you share the exact error from check50 and confirm whether you're working at cs50.dev or in a Codespace created directly from GitHub? That would help determine whether this is an authentication issue or something else. — Reply to this email directly, view it on GitHub <#209696?email_source=notifications&email_token=APP5AHXRRJSO46Q56MY5DT35TC567A5CNFSNUABIM5UWIORPF5TWS5BNNB2WEL2ENFZWG5LTONUW63SDN5WW2ZLOOQXTCOBYGMZTKNJSUZZGKYLTN5XKO3LFNZ2GS33OUVSXMZLOOSWGM33PORSXEX3DNRUWG2Y#discussioncomment-18833552>, or unsubscribe <http://github.com/notifications/unsubscribe-auth/APP5AHWZWP6ENPM2TT3CCYD5TC567AVCNFSNUABIKJSXA33TNF2G64TZHMZTAMJVG4ZTGNBUHNCGS43DOVZXG2LPNY5TCMBZGY2TGNBQUF3AE>. Triage notifications, keep track of coding agent tasks and review pull requests on the go with GitHub Mobile for iOS <http://github.com/notifications/mobile/ios/APP5AHWIWSDWRX5X242KHK35TC567A5CNFSNUABIM5UWIORPF5TWS5BNNB2WEL2ENFZWG5LTONUW63SDN5WW2ZLOOQXTCOBYGMZTKNJSUZZGKYLTN5XKO3LFNZ2GS33OUVSXMZLOOSVGM33PORSXEX3JN5ZQ> and Android <http://github.com/notifications/mobile/android/APP5AHQSECYZLAMPFZTJWPD5TC567A5CNFSNUABIM5UWIORPF5TWS5BNNB2WEL2ENFZWG5LTONUW63SDN5WW2ZLOOQXTCOBYGMZTKNJSUZZGKYLTN5XKO3LFNZ2GS33OUVSXMZLOOSXGM33PORSXEX3BNZSHE33JMQ>. Download it today! You are receiving this because you were mentioned.