Update Android SDK from v2 to v3

Move an existing PayPal Mobile SDK v2.x Android integration to v3.0.0. Plan for a client rename and a new required merchantId, plus moving return URLs out of your Orders API call, which affects both your app and your server.

The largest changes are in PayPal Checkout:

• PayPal renamed the client.
• Checkout is now session-first.
• CoreConfig requires a merchantId.
• Return URLs moved out of the Orders API into a URL config.

What's changed in PayPal Checkout

The following table summarizes the key PayPal Checkout changes from v2 to v3.

Card (ACDC) keeps its own client; the main change it inherits is the merchantId on CoreConfig. Card's approveOrder() / presentAuthChallenge() / finishApproveOrder() result-type pattern is unchanged from 2.x.

Before you upgrade

• Get your merchant ID, the encrypted merchant account ID, from the PayPal Developer Dashboard. The SDK now requires it to initialize.
• The toolchain is unchanged from late v2.x: Java 17, a recent Android Gradle Plugin, and a compatible Kotlin version.

Update the dependency

Bump each PayPal module to the v3 release. PayPal renamed the PayPal Checkout artifact from paypal-web-payments to paypal-payments. The other module names are unchanged:

dependencies {
    implementation 'com.paypal.android:paypal-payments:3.0.0'   // was paypal-web-payments in v2
    implementation 'com.paypal.android:payment-buttons:3.0.0'
    implementation 'com.paypal.android:fraud-protection:3.0.0'
}

Migrate PayPal Checkout

Use this diff to guide the change:

  val config = CoreConfig(
      clientId = "<CLIENT_ID>",
+     merchantId = "<MERCHANT_ID>",   // now required, distinct from your client ID
-     environment = Environment.SANDBOX
+     coreEnvironment = CoreEnvironment.SANDBOX   // renamed from `environment` in v3
  )

- val client = PayPalWebCheckoutClient(context, config, "my-url-scheme")
+ val client = PayPalClient(context, config)
+ val urlConfig = ReturnToAppUrlConfig(
+     returnAppUrl = "https://example.com/merchant-app/return",
+     cancelAppUrl = "https://example.com/merchant-app/cancel",
+     fallbackSchemeUrl = "merchantapp://return"
+ )

  fun onPayPalButtonTapped() {
+     // NEW: prepare the session before start()
+     client.createPayPalSession(
+         tokenType = TokenType.ORDER_ID,
+         userIdentity = PayPalUserIdentity(email = "[email protected]"),
+         urlConfig = urlConfig,
+         userAction = PayPalUserAction.CONTINUE
+     )
      val orderId = myServer.createOrder()
-     client.start(this, PayPalWebCheckoutRequest(orderId)) { /* PayPalPresentAuthChallengeResult */ }
+     client.start(this, orderId, object : PayPalResultCallback {
+         override fun onPayPalResult(result: PayPalPresentAuthChallengeResult) {
+             when (result) {
+                 is PayPalPresentAuthChallengeResult.Success -> { /* checkout UI presented; the outcome arrives in onNewIntent */ }
+                 is PayPalPresentAuthChallengeResult.Failure -> showError(result.error)
+             }
+         }
+     })
  }

  override fun onNewIntent(intent: Intent) {
      super.onNewIntent(intent)
      setIntent(intent)
-     client.finishStart(intent)?.let { /* PayPalWebCheckoutFinishStartResult */ }
+     client.finishStart(intent)?.let { result ->
+         when (result) {
+             is PayPalFinishStartResult.Success -> captureOrder(result.orderId)
+             is PayPalFinishStartResult.Canceled -> showCheckoutScreen()
+             is PayPalFinishStartResult.Failure -> showError(result.error)
+             PayPalFinishStartResult.NoResult -> { /* intent was not a checkout return */ }
+         }
+     }
  }

Server-side change

In v2, you set experienceContext.returnUrl / cancelUrl when creating the order. In v3, those move to the SDK through ReturnToAppUrlConfig. Remove them from your Orders v2 create call for the session-based flow. Your manifest App Link and custom-scheme fallback stay as they were.

Pay Later and PayPal Credit

In v2, selecting PAY_LATER / PAYPAL_CREDIT funding required the non-session start(activity, request: PayPalWebCheckoutRequest, callback) overload. v3 removed both that overload and PayPalWebCheckoutRequest.

Funding-source selection moves entirely to your server: set payment_source.paypal.experience_context.payment_method_selected to PAYPAL (default), PAYPAL_PAY_LATER, or PAYPAL_CREDIT when you create the order. The client-side createPayPalSession() → start(activity, orderId, callback) flow is identical regardless of funding source.

Verify the upgrade

• The project compiles with PayPalClient and no references to PayPalWebCheckoutClient remain.
• A sandbox checkout completes end to end: createPayPalSession() → start(activity, orderId, callback) → finishStart(intent) in onNewIntent → capture.
• The PayPalEvent.SESSION_NOT_STARTED event does not fire, confirming createPayPalSession() runs before start().

See also

• Install and set up: add the SDK, initialize CoreConfig, and register your return links.
• PayPal Checkout: integrate one-time checkout, save payment methods, Pay Later, and PayPal Credit.
• Troubleshooting: diagnose common build and integration failures by symptom.