A while ago, OpenAI’s Codex became available to Plus users as well. I had been contemplating “I want to use Codex, should I subscribe?” after seeing reviews from Pro users, so I was absolutely thrilled.
I tried out Codex to check its usability, but I ran into an unexpected trap, so I’m leaving this note for reference.
Table of Contents
What is Codex
A cloud-based software engineering agent developed by OpenAI. The initial version uses a model called codex-1, which is based on the o3 foundation model.
Error: Simply Creating a GitHub Repository Isn’t Enough
When I created a GitHub repository and tried to have it build an app by entering a prompt, the following error occurred:
“GitHub repository needs to be initialized for use within Codex.”
I was puzzled, thinking “The repository exists, so what does initialization mean?” But the solution is simple: add a README and commit once.
Solution Steps
IMPORTANTThe issue can be resolved by adding a README file and committing it. Choose one of the following methods:
Method 1: Using GUI
In the GitHub repository screen, click the + button, then Add file → Create new file, create README.md, and click “Commit new file” (the content can be anything).
Method 2: Using Local Development
Create README.md → git add README.md && git commit -m "docs: add README" → git push origin main (or your default branch name).
Common: Re-run in Codex
Run the prompt again in Codex, and the error will be resolved.
Conclusion
After adding a README and committing it, the error no longer occurs.
It makes sense that an LLM doesn’t work well without input, but I think the system could have prepared this automatically… Still, Codex is incredibly useful. I’m planning to write a tutorial article for fun later.
Here’s the GitHub repository I used for this:
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