IMPORTANT: This changelog has been superseded. This breaking change has been consolidated with two others into a single entry, and the date is now July 17, 2026. Please refer to the updated changelog for up-to-date details. The information below is retained for reference only.
On July 8th, 2026, CircleCI is updating how undeclared parameters are handled. Previously, referencing a parameter that is not declared in the current scope could silently resolve instead of raising an error, allowing invalid configs to compile.
After this date, configs that reference an undeclared parameter will fail to compile. You can preview whether your config is affected today using the “config next” validation in the UI or the CLI.
For more information, see our Discuss post.