Old API domain is expiring and won't be renewed — will old app versions on users' phones fail to connect after switching to a new domain?

When an app needs to change its API domain after launch, whether old versions on users' phones will lose connection is not a simple yes or no — it depends on where the old version gets the API address from. If the domain is hardcoded in the installer, old versions usually fail requests as soon as the server side switches. If the domain comes from remote config, or the old domain keeps resolving and forwarding to the new service, most old versions can keep running. By 2026 delivery practice, a domain change should be managed as a compatibility change: first inventory where the domain is hardcoded in the client, then decide how long to keep the old domain — not treat it as a one-off ops task.

When changing the API domain, whether old versions break starts with which layer the domain is written into

An API domain is the entry address the app uses to reach the backend. It does not appear only in the main API — it can also be buried in third-party SDK initialization, image and file URLs, WebView home pages, payment callbacks, and push deep links. When old versions cannot connect, it is often not the whole service going down, but one of these spots still pointing at an old domain that has already been shut off.

So the order of checks is: first, see whether the client hardcodes the domain; second, see whether the old domain can still resolve and forward; third, see whether edge configuration has been synced. Watching only the main API easily misses broken images, H5 pages that will not open, and lost payment callbacks.

• Client-side hardcoding: the domain is written into the installer, so a domain change requires a new release; otherwise old versions can only be covered by old-domain forwarding.
• Remote config: the domain is read from remote config or an API and can be switched dynamically, but old versions must still be able to route the old config they already read to the new service.
• Third-party backend configuration: domains filled into payment callbacks, push certificates, WeChat sharing, and map SDKs must be updated in sync after the domain change.
• Certificates and protocols: if the new domain's certificate does not cover the old domain, or HTTPS configuration is not synced, old versions will report network errors directly.

Changing the main domain, a subdomain, or an asset domain: where does the impact differ?

Changing a domain is not a single action. There are three common types: changing the main domain, changing a subdomain, and changing an asset domain. They affect old versions differently and need to be handled in a different order.

• Changing the main domain: broader impact — API, share links, and callback addresses may all change. If the old main domain is taken offline directly, old versions usually cannot send requests; keeping the old domain for forwarding is a common fallback.
• Changing a subdomain: medium impact, usually limited to APIs or image assets. Watch whether the subdomain certificate, CORS configuration, and CDN cache are synced.
• Changing an asset domain: affects images, videos, and file downloads. Old versions may still log in, but images fail to load, which users perceive as a broken layout.
• Changing protocol or port: moving from HTTP to HTTPS, or changing the default port, may trigger iOS and Android network security policies; old versions may not adapt automatically.

In common 2026 practice, a main domain migration usually requires a client compatibility release, server-side forwarding, and third-party platform configuration updates in parallel; asset domain migration can be rolled out gradually earlier because the impact is relatively contained.

Keeping old-domain forwarding versus forcing an update: how much do cost and timeline differ?

The choice between these two paths usually does not depend on technical difficulty, but on how many active users are still on old versions and whether core flows depend on old versions. Below is a checkable comparison based on experience ranges.

• Keep old-domain forwarding: old domain renewal and certificate typically range from tens to hundreds of RMB per year; adding forwarding or reverse proxy rules on the server usually takes 0.5 to 2 person-days; typical retention period is 3 to 12 months.
• Force an update and retire the old domain: client changes plus app review typically range from 3 to 10 business days; if old-version users are a significant share, customer support inquiries and churn will rise in the short term, and the recovery period is uncertain.
• Hybrid approach: new versions use the new domain while old versions use old-domain forwarding, with a gentle update prompt; a typical pattern is to run in parallel for 1 to 3 months, then decide whether to close it out based on the active share of old versions.

These numbers are experience ranges, not a quote. What really needs checking is whether the old domain expiration date, certificate validity, payment callback addresses, CORS configuration, and domains in third-party backends are all on the same checklist.

From the delivery floor: a lesson from a migration raised only when the old domain was about to expire

We once ran into a typical situation: the client had a tight budget and timeline, the old domain was less than a month from expiring, and the client wanted to shut it down directly, switch everything to the new domain, and stop renewing. The constraint was that the app had been live for over a year, a significant share of existing users were still on old versions, and the old client hardcoded both the API domain and the image domain in the installer.

What we did was split into two steps: first use the old domain for forwarding so requests were routed to the new service, keeping old versions able to log in and place orders; at the same time, update the domains in payment callbacks, push deep links, and the WebView home page, then schedule a new release and gradual rollout. The result was that core flows on old versions did not break during the transition. The cost was renewing the old domain for another year and spending about 1 extra person-day on forwarding configuration and regression verification.

If the old domain had been shut down directly as originally planned, experience ranges suggest old users would most likely flood in with reports of pages not opening or white screens within a day or two. Buying the domain back temporarily and reconfiguring the certificate and forwarding usually takes more time than keeping it in advance, and is more likely to hurt conversion during that period.

When to keep the old domain and when a forced update is enough

To set the boundary, look at two things first: whether old versions are still within the support window, and whether old versions can still complete core flows such as login, ordering, and payment.

• When keeping old-domain forwarding fits: the app is already live with existing users, old versions can still complete core flows, payment callbacks rely on the old address, a forced update would clearly hurt conversion, or the old domain must be replaced due to ICP filing, entity change, or provider migration.
• When a forced update fits: the app is not live yet or has only internal test users, old versions are no longer maintained, the share of old-version users is very low, and customer support and operations can absorb the short-term churn from a forced update.
• Boundary reminder: as long as old versions still have active users and core flows are not broken, keeping old-domain forwarding is usually safer; if old versions are past their maintenance window and the business allows forced updates, switching domains directly with a forced update is often more cost-effective than keeping the old domain long term.

Frequently asked questions

After an app changes domains, will old versions definitely fail to open?

Not necessarily. It depends on whether the old domain keeps resolving and forwarding to the new service. If it is taken offline directly and the client hardcodes it, old versions usually fail requests, showing a white screen or a network error.

How long should the old domain be kept?

Based on 2026 delivery experience, the typical range is 3 to 12 months. It depends on the share of old-version users and whether the business allows forced updates; projects with many existing users often keep it longer.

Can we just ship a forced update and skip dealing with the old domain?

Yes, but a forced update turns a technical problem into user churn. First check whether old versions can still complete core flows; if old versions are no longer maintained and active users are few, a forced update saves more cost.

Does changing the domain require resubmitting the app to the store?

If the client hardcodes the domain, you need a new release and app review after the change. If the domain comes from remote config or old-domain forwarding, resubmission may not be needed, but new versions should still replace it gradually.

What is easily missed when changing domains?

Common misses are image and file URLs, the WebView home page, payment callback addresses, push deep links, and domains configured in third-party SDK backends. The main API is often not the only entry point.

Before changing an API domain, inventory the client's hardcoded locations first, then decide how long to keep the old domain. This fits projects already live with existing users; if the app is not live yet, or old versions are no longer maintained and forced updates are allowed, there is no need to invest extra in keeping the old domain. In 2026 delivery practice, putting domain migration on the acceptance checklist saves more rework than fighting fires afterward.