Capacitor App Upgrade v5 to v6

Move a Capacitor 5 app to Capacitor 6. Source of truth: https://capacitorjs.com/docs/updating/6-0

When to Use

• @capacitor/core in the snapshot below is 5.x and the user wants 6.x.
• After upgrading: Android users lose localStorage/cookies, a local (non-npm) iOS plugin reports "<Name>" plugin is not implemented on ios, pinch-zoom stopped working on iOS, or TypeScript errors around addListener.
• The user asks for the exact 5 -> 6 checklist.

Do not use:

• App on 4.x -> capacitor-app-upgrade-v4-to-v5 first. On 6.x -> capacitor-app-upgrade-v6-to-v7. Multi-hop planning -> capacitor-app-upgrades.
• Plugin library upgrade -> capacitor-plugin-upgrade-v5-to-v6.
• Moving iOS from CocoaPods to SPM (experimental in 6) -> cocoapods-to-spm.

Live Project Snapshot

Current Capacitor packages from package.json: !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=[];for(const section of ['dependencies','devDependencies']){for(const [name,version] of Object.entries(pkg[section]||{})){if(name.startsWith('@capacitor/'))out.push(section+'.'+name+'='+version)}}console.log(out.sort().join('\n'))"

References

Only load a reference when its topic is in play.

Preflight

node -v && xcodebuild -version && java -version
git status --short
grep -rn "androidScheme" capacitor.config.*   # decide the scheme BEFORE migrating

Procedure

1. Confirm 5.x from the snapshot.
2. Decide androidScheme first (judgement call, ask the user if unclear). Capacitor 6 defaults existing apps to https. Changing scheme changes the WebView origin, so localStorage, IndexedDB, cookies and service workers from the installed app are no longer readable.
   • No androidScheme set today -> add server: { androidScheme: "http" } to keep user data.
   • Already "https" -> the entry can be removed.

3. Run the automated migration:

   npm i -D @capacitor/cli@latest-6
   npx cap migrate

   Read the output and finish every step it reports as failed.

4. iOS:
   • Plugin classes are no longer auto-registered. npm plugins are handled by the CLI-generated list. Local plugins written in the app target (custom code guide) need a CAPBridgeViewController subclass that overrides capacitorDidLoad() and calls bridge?.registerPluginInstance(MyPlugin()), and Main.storyboard must use that subclass as the view controller's custom class.
   • Zoom is disabled by default. If the app relied on pinch zoom, set zoomEnabled: true in the Capacitor config.
5. Android: apply references/android.md (AGP 8.2.1, Gradle 8.2.1, google-services 4.4.0, compileSdk, Kotlin 1.9.10).
6. Update all @capacitor/* plugins to ^6.0.0 and community plugins to their Capacitor 6 releases. Fix code per references/plugins.md.
7. Run verification.

Traps

• addListener now returns only Promise<PluginListenerHandle>. const h = Plugin.addListener(...); h.remove() no longer compiles; use const h = await Plugin.addListener(...).
• Camera now uses the Android Photo Picker. Gallery cancel rejects with "User cancelled photos app" on Android, like other platforms; update error matching.
• Filesystem stat() on iOS returns ctime / mtime as numbers, not strings.
• Do not remove READ_MEDIA_IMAGES / storage permissions if saveToGallery: true or another plugin needs them.

Verification

grep -rn "androidScheme" capacitor.config.*                 # explicit decision recorded
grep -n "compileSdkVersion rootProject" android/app/build.gradle   # expect none (now compileSdk)
grep -n "gradle:8.2.1\|google-services:4.4.0" android/build.gradle
grep -n "distributionUrl" android/gradle/wrapper/gradle-wrapper.properties   # gradle-8.2.1
grep -n "SdkVersion" android/variables.gradle                # 22 / 34 / 34
grep -rnE "= *[A-Za-z]+\.addListener\(" src/                 # each must be awaited
grep -rn "registerPluginInstance" ios/App/App/               # present if the app has local plugins
npx cap sync
cd android && ./gradlew assembleDebug

Build and launch iOS in Xcode 15+. On a device that had the v5 build installed, upgrade in place and confirm login/localStorage survived.

Error Handling