Diary

Bottom line: if you submit an update with a targetSdkVersion lower than what Google Play requires, it gets rejected at upload time. That means you can’t push updates to the store at all. This isn’t about new features — it’s a mandatory requirement to keep delivering updates to existing users and maintain your store listing.

Google Play has been raising the minimum targetSdkVersion by one level every August 31. Currently (August 2025 onward), all updates below API 35 (Android 15) are rejected.

(Source: Google Play target API level requirements)

Based on this pattern, enforcement of API 36 (Android 16) is most likely around August 2026. To complete compliance before enforcement kicks in, this article scopes the work by working backward from an internal deadline of June 2026. Android 17 has reached platform stability at Beta 3, so running early verification in a parallel lane now means you won’t be scrambling when the final release drops.

Priority Order

Get Your Tooling in Order First

Whether you’re working on Android 16 compliance or early Android 17 verification, the first blockers are usually build tooling issues rather than OS APIs. Lock down the tooling first.

plugins {
    id("com.android.application") version "9.1.0" apply false
    id("org.jetbrains.kotlin.android") version "2.3.20" apply false
}

Locking JDK 17 in CI, updating AGP, and absorbing R8 differences serves double duty — it lays the groundwork for Android 17 while getting Android 16 compliance through the door.

Note: Real-World Kotlin Version Distribution and Migration Cost

The “Kotlin 2.3.20” in the table above is the recommended baseline. In practice, many projects are still on the 1.9.x line. Finance, government, and large-scale projects in Japan tend to be particularly conservative — the “it’s stable, so don’t upgrade” mindset persists for a long time.

The chart below is an estimate as of early 2026 based on JetBrains’ public ecosystem data and community observations.

(Estimated values. For exact version-level share data, refer to the latest JetBrains Developer Ecosystem Survey)

When upgrading from 1.9.x to 2.x, it’s rarely just a Kotlin-only update — it usually means a bulk upgrade of Compose, Coroutines, and AGP together. Switching to the K2 compiler can change some type inference behavior, causing build errors. “We don’t need to upgrade our working 1.9.x app right now” is a perfectly pragmatic decision.

Android 17 Behavior Changes to Get Ahead Of

Behavior changes have a bigger impact on existing apps than new features. Focus on changes that affect all apps first.

Testing Priority for Simultaneous Android 16 & 17 Support

When running Android 16 compliance and Android 17 early verification in parallel, it’s easy to lose track of what must be tested where. The table below defines required/priority items per test area — use it as a QA checkpoint to confirm when each area can be considered done.

Risks Specific to Japanese Business Apps

These points are rarely covered in general Android migration articles from international sources, but finance, government, and membership-platform apps in Japan have their own specific gotchas. For projects where the priority is verifying that existing key flows — login, payments, notifications — aren’t broken rather than adopting new Android 16/17 features (notification channel changes, permission model overhauls, new Compose components, etc.), run through the items below as a checklist first.

Recommended Action Order

1. Finalize the release plan with the assumption that the targetSdkVersion 36 (Android 16) update ships by June 2026
2. Align your tooling: Android Studio, AGP, Kotlin, JDK
3. Run key user flow tests and regression for Android 16 first
4. In parallel, create a dedicated Android 17 branch and spin up a verification lane with emulators and real devices
5. Work through behavior changes in order: security, media, connectivity
6. Run a separate CI pipeline with targetSdk 37

In an Nginx reverse proxy setup where the frontend Nginx accepts requests on 443 (HTTPS) and performs round-robin load balancing internally on 80 (HTTP), you may encounter a Mixed Content error in Chrome.

To fix this, add the following to the top of wp-config.php:

/** mixed content the page at ' url ' was loaded over https wordpress nginx */
/** When using proxy settings, you need to set it to redirect via https! */
/** Note: The HTTP_X_FORWARDED_FOR environment variable name may vary slightly depending on your server environment (AWS, etc.), so verify it */
if (!empty($_SERVER['HTTP_X_FORWARDED_FOR'])) {
    $_SERVER['HTTPS'] = 'on';
}

If you can modify the nginx.conf file on the internal 80 (HTTP) side, you can also use this approach:

Either option works fine.

location ~ \.php$ {
    include fastcgi_params;

    # mixed content the page at ' url ' was loaded over https wordpress nginx
    # When using proxy settings, you need to set it to redirect via https! From here
    fastcgi_param HTTPS on;
    fastcgi_param HTTP_X_FORWARDED_PROTO https;
    # To here

    fastcgi_intercept_errors on;
    fastcgi_pass php-fpm;
    fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
}

Ruby 3.2.6

Ruby on Rails 7.0.8.7

Fails on startup

The cause is the gem

gem 'concurrent-ruby', '1.3.5'

Add to the end of Gemfile and pin it for now

gem 'concurrent-ruby', '1.3.4'

bundle install

# Fetching concurrent-ruby 1.3.4 (was 1.3.5)
# Installing concurrent-ruby 1.3.4 (was 1.3.5)

Error log below

# With gem 'concurrent-ruby', '1.3.5' you get the error below, so pinning to '1.3.4'
#
# bundler: failed to load command: puma (/app-root/vendor/bundle/ruby/3.2.0/bin/puma)
# /app-root/vendor/bundle/ruby/3.2.0/gems/activesupport-7.0.8.7/lib/active_support/logger_thread_safe_level.rb:12:in `<module:LoggerThreadSafeLevel>': uninitialized constant ActiveSupport::LoggerThreadSafeLevel::Logger (NameError)
#
# Logger::Severity.constants.each do |severity|
# ^^^^^^^^^^

Tried to renew a certificate, but the Keychain Access icon is gone?

macOS Sequoia 15 and later changed how you launch it.

A “Passwords” app is now the main thing displayed, and Keychain Access—which engineers need—seems to have been hidden.

The underlying data is probably the same, but the Passwords app is a simplified interface for usability.

How to access it

Hit Command + Space to open Spotlight and type “key”—the icon will show up.

Apple’s official docs cover this too.

Download Windows 11 (hereafter, 24H2) from Microsoft’s official download site

Run the following command to launch the 24H2 installer

Navigate to the current drive mounted in cmd prompt and

setup /product server