I took a look through the existing Codex issues to see whether this has already been reported. I did not find any issues that are close enough to this one to consider them a match or worth linking as a related issue.
There are many reports involving failed file access, but they vary significantly in their specific symptoms, circumstances, and underlying causes.
Search the existing Codex issues for an existing issue. If you cannot find one, consider opening a new issue and include as much relevant information as possible, such as your Codex version, operating system, environment, reproduction steps, expected behavior, actual behavior, and any relevant logs or error messages.
If you find an issue that describes the same problem you are experiencing, consider adding a 
reaction to the GitHub issue itself. GitHub reactions can help the maintainers gauge how many users are affected.