Capacitor Plugin Upgrade v7 to v8

Move a plugin library to Capacitor 8. Source of truth: https://capacitorjs.com/docs/updating/plugins/8-0

When to Use

• Snapshot shows @capacitor/core 7.x and the plugin must work in Capacitor 8 apps.
• Building the plugin against Kotlin 2.2 fails on kotlinOptions or kotlin-android-extensions.
• Gradle warns Properties should be assigned using the 'propName = value' syntax.

Do not use:

• Upgrading an app -> capacitor-app-upgrade-v7-to-v8.
• Plugin on 6.x -> capacitor-plugin-upgrade-v6-to-v7 first. Multi-hop -> capacitor-plugin-upgrades.
• Plugin already on 8.x -> capacitor-plugin-upgrade-v8-to-v9.
• Adding SPM -> capacitor-plugin-spm-support.

Live Project Snapshot

Plugin and Capacitor package snapshot: !node -e "const fs=require('fs');if(!fs.existsSync('package.json'))process.exit(0);const pkg=JSON.parse(fs.readFileSync('package.json','utf8'));const out=['package.name='+(pkg.name||''),'package.version='+(pkg.version||'')];for(const section of ['peerDependencies','dependencies','devDependencies']){for(const [name,version] of Object.entries(pkg[section]||{})){if(name.startsWith('@capacitor/'))out.push(section+'.'+name+'='+version)}}console.log(out.join('\n'))"

Example and native project paths: !find . -maxdepth 3 \( -path './example-app' -o -path './ios' -o -path './android' \)

References

Preflight

Procedure

1. Confirm 7.x and a clean tree.

2. From the plugin root:

   npx @capacitor/plugin-migration-v7-to-v8@latest

   Review git diff.

3. package.json: dev deps @capacitor/cli, core, android, ios to ^8.0.0; peer @capacitor/core to >=8.0.0.
4. Android per references/android.md:
   • Only add/update the ext {} dependency defaults the plugin actually uses.
   • SDK defaults 24/36/36, AGP 8.13.0, Gradle 8.14.3, google-services 4.4.4 (if used).
   • Convert every property assignment to = (namespace = ..., compileSdk = ..., url = ..., abortOnError = ...). Method calls such as mavenCentral() stay unchanged.
   • Java 21 compileOptions.
   • Kotlin plugins: kotlin_version 2.2.20, replace kotlinOptions {} with kotlin { compilerOptions { jvmTarget = JvmTarget.JVM_21 } }, drop kotlin-android-extensions (use kotlin-parcelize / view binding).
   • Code referencing R.layout.bridge_layout_main must use capacitor_bridge_layout_main.
5. iOS per references/ios.md: podspec 15.0, Package.swift .iOS(.v15), capacitor-swift-pm from: "8.0.0". If the plugin posted .capacitorViewDidAppear / .capacitorViewWillTransition itself, remove that code; Capacitor 8 emits them.
6. Upgrade the example app via capacitor-app-upgrade-v7-to-v8, bump the plugin major, note "Requires Capacitor 8".

After 8.x: next steps

• Capacitor 8.5 apps adopt the iOS UIScene lifecycle (required by Xcode 27). Plugins that hook AppDelegate methods (application(_:open:options:), continue userActivity, applicationDidBecomeActive, ...) or use UIApplication.shared.windows / keyWindow must handle scene-based apps; see capacitor-uiscene-migration.
• Then capacitor-plugin-upgrade-v8-to-v9 (Capacitor 9 is on next, not GA).

Verification

grep -n "\"@capacitor/" package.json                                    # ^8.0.0 / >=8.0.0
grep -nE "^\s*(namespace|compileSdk|url|abortOnError|minSdkVersion|targetSdkVersion) [^=]" android/build.gradle   # expect none
grep -n "kotlinOptions\|kotlin-android-extensions" android/build.gradle # expect none
grep -n "VERSION_21\|gradle:8.13.0" android/build.gradle
grep -n "distributionUrl" android/gradle/wrapper/gradle-wrapper.properties   # gradle-8.14.3
grep -rn "bridge_layout_main" android/src | grep -v capacitor_bridge   # expect none
grep -n "deployment_target" *.podspec                                  # '15.0'
grep -n "iOS(\|capacitor-swift-pm" Package.swift 2>/dev/null           # .v15, from: "8.0.0"
npm run build
npm run verify         # if the repo has the template verify scripts
cd android && ./gradlew build --warning-mode all

Run the example app on both platforms.

Error Handling