How Do You Handle Stale Frontend Bundles During Breaking API Changes?

For a simple app, catch the failure and trigger a refresh. It’s quick and usually solves the problem, although you should avoid creating a reload loop if the new build still has an issue.

Version the frontend assets so browsers and CDNs don’t keep serving stale files. Content-hashed filenames, such as those generated by Vite and similar build tools, are a good cache-busting strategy. For the API itself, backward compatibility is preferable; if that isn’t practical, expose a new API version such as /v2 rather than breaking existing clients.

A smoother option is to have every API response include the current frontend or deployment version in a header. The frontend can compare that value with the build version embedded at compile time. If they differ, show a message saying a new version is available and offer a refresh, instead of letting an unrelated API request fail unexpectedly.

The usual approach is to keep normal API changes backward-compatible and deploy backend changes before the frontend. For genuinely breaking changes, schedule the deployment and monitor which frontend build numbers are still active. Once the incompatible build is no longer being used, deploy the API change. You can include the build number in frontend telemetry through tools such as Application Insights or OpenTelemetry.