diff --git a/examples/apm/index.html b/examples/apm/index.html
index df393ada..e23e6d6d 100644
--- a/examples/apm/index.html
+++ b/examples/apm/index.html
@@ -26,6 +26,7 @@
       <label><input type="checkbox" id="redirect-headless" /> Enable headless mode (skip &ldquo;Continue to payment&rdquo; / Pay; open PSP immediately)</label>
       <label style="margin-left: 1.25rem;"><input type="checkbox" id="redirect-silent-failure" disabled /> Silent failure view (headless: no in-widget error; listen for <code>failure</code>)</label>
       <label style="margin-left: 1.25rem;"><input type="checkbox" id="redirect-show-loader" checked disabled /> Show headless loader while opening PSP</label>
+      <label style="margin-left: 1.25rem;"><input type="checkbox" id="redirect-popup-blocked-overlay" checked disabled /> SDK overlay on popup-blocked (default <code>true</code>; uncheck to suppress and handle <code>redirect-popup-blocked</code> yourself)</label>
       <label><input type="checkbox" id="redirect-overlay-root" /> Mount PSP action overlay on <code>#action-overlay-root</code> instead of <code>document.body</code></label>
     </div>
   </fieldset>
@@ -82,9 +83,11 @@
       const headless = document.getElementById('redirect-headless').checked;
       document.getElementById('redirect-silent-failure').disabled = !headless;
       document.getElementById('redirect-show-loader').disabled = !headless;
+      document.getElementById('redirect-popup-blocked-overlay').disabled = !headless;
       if (!headless) {
         document.getElementById('redirect-silent-failure').checked = false;
         document.getElementById('redirect-show-loader').checked = true;
+        document.getElementById('redirect-popup-blocked-overlay').checked = true;
       }
     }
 
@@ -103,6 +106,9 @@
       if (document.getElementById('redirect-headless').checked && !document.getElementById('redirect-show-loader').checked) {
         redirect.showHeadlessLoader = false;
       }
+      if (document.getElementById('redirect-headless').checked && !document.getElementById('redirect-popup-blocked-overlay').checked) {
+        redirect.popupBlockedOverlay = false;
+      }
       if (document.getElementById('redirect-overlay-root').checked) {
         redirect.actionOverlayMountParent = document.getElementById('action-overlay-root');
       }
@@ -211,6 +217,25 @@
           }
         })
 
+        // redirect-popup-blocked fires when the headless auto-open was blocked by the browser
+        // (e.g. Safari). By default the SDK shows its own Pay button overlay automatically.
+        // When popupBlockedOverlay: false is set, handle it here instead.
+        apm.on('redirect-popup-blocked', function (data) {
+          if (document.getElementById('redirect-popup-blocked-overlay').checked) return; // SDK overlay or forceUpdate is handling it
+          // Example custom UI: a simple fixed overlay with a retry button
+          var overlay = document.createElement('div');
+          overlay.style.cssText = 'position:fixed;inset:0;z-index:2147483647;display:flex;align-items:center;justify-content:center;padding:16px;background:rgba(0,0,0,0.5);';
+          var btn = document.createElement('button');
+          btn.textContent = 'Continue to payment';
+          btn.style.cssText = 'padding:0.75em 1.5em;font-size:1rem;cursor:pointer;';
+          btn.onclick = function () {
+            overlay.remove();
+            data.retry();
+          };
+          overlay.appendChild(btn);
+          document.body.appendChild(overlay);
+        })
+
         try {
           apm.initialise()
         } catch (e) {
diff --git a/package.json b/package.json
index 0fbe768b..0fd800c5 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "processout.js",
-  "version": "1.8.8",
+  "version": "1.8.9",
   "description": "ProcessOut.js is a JavaScript library for ProcessOut's payment processing API.",
   "scripts": {
     "build:processout": "tsc -p src/processout && uglifyjs --compress --keep-fnames --ie8 dist/processout.js -o dist/processout.js",
diff --git a/src/apm/API.ts b/src/apm/API.ts
index 14cbe83c..64dbedb3 100644
--- a/src/apm/API.ts
+++ b/src/apm/API.ts
@@ -209,6 +209,8 @@ module ProcessOut {
   let INITIAL_MAX_RETRIES = 0
   let POLLING_TIMEOUT_ID: number | null = null
   let POLLING_CANCELLED = false // Add cancellation flag
+  /** Bumped on each makeRequest and on cancelPolling so stale responses / timers cannot duplicate polls. */
+  let POLLING_GENERATION = 0
 
   const isErrorResponse = (data: AuthorizationNetworkResponse | TokenizationNetworkResponse): data is NetworkErrorResponse => {
     const hasInvalidFields = 'invalid_fields' in data;
@@ -391,6 +393,13 @@ module ProcessOut {
         };
       }
 
+      const requestGen = ++POLLING_GENERATION;
+      if (POLLING_TIMEOUT_ID) {
+        window.clearTimeout(POLLING_TIMEOUT_ID);
+        POLLING_TIMEOUT_ID = null;
+      }
+      POLLING_CANCELLED = false;
+
       if (INITIAL_MAX_RETRIES === 0) {
         INITIAL_MAX_RETRIES = internalOptions.serviceRetries;
       }
@@ -413,6 +422,10 @@ module ProcessOut {
         endpoint,
         data,
         (apiResponse: AuthorizationNetworkResponse | TokenizationNetworkResponse) => {
+          if (requestGen !== POLLING_GENERATION) {
+            return;
+          }
+
           if (isErrorResponse(apiResponse)) {
             INITIAL_MAX_RETRIES = 0;
             
@@ -513,11 +526,10 @@ module ProcessOut {
               }
             }
 
-            // Continue polling in background (only if not cancelled)
+            // Continue polling in background (only if not cancelled and this chain is still current)
             if (!POLLING_CANCELLED) {
               POLLING_TIMEOUT_ID = window.setTimeout(() => {
-                // Double-check cancellation before continuing
-                if (!POLLING_CANCELLED) {
+                if (!POLLING_CANCELLED && requestGen === POLLING_GENERATION) {
                   internalOptions.serviceRetries = INITIAL_MAX_RETRIES
                   this.getCurrentStep(internalOptions);
                 }
@@ -554,8 +566,16 @@ module ProcessOut {
           return;
         },
         (req, _, errorCode) => {
+          if (requestGen !== POLLING_GENERATION) {
+            return;
+          }
+
           if ((req.status === 0 || req.status > 500) && internalOptions.serviceRetries > 0) {
+            const retryGen = POLLING_GENERATION;
             setTimeout(() => {
+              if (retryGen !== POLLING_GENERATION) {
+                return;
+              }
               internalOptions.serviceRetries--;
               this.makeRequest(method, pathOrOptions, data, internalOptions)
             }, TIMEOUT * ((INITIAL_MAX_RETRIES - internalOptions.serviceRetries) + 1));
@@ -629,7 +649,8 @@ module ProcessOut {
     }
 
     public static cancelPolling(): void {
-      POLLING_CANCELLED = true; // Set cancellation flag
+      POLLING_CANCELLED = true;
+      POLLING_GENERATION++;
       if (POLLING_TIMEOUT_ID) {
         window.clearTimeout(POLLING_TIMEOUT_ID);
         POLLING_TIMEOUT_ID = null;
diff --git a/src/apm/Context.ts b/src/apm/Context.ts
index 35c9f49f..dd56f14a 100644
--- a/src/apm/Context.ts
+++ b/src/apm/Context.ts
@@ -62,6 +62,12 @@ module ProcessOut {
        * Append `ActionHandler` iframe modal / new-window overlay to this element instead of `document.body`.
        */
       actionOverlayMountParent?: HTMLElement | null
+      /**
+       * When the headless popup is blocked, mount the SDK's built-in Pay button modal
+       * overlay directly on `document.body`. Default `true`.
+       * Set to `false` to suppress the SDK overlay and handle `redirect-popup-blocked` yourself.
+       */
+      popupBlockedOverlay?: boolean
     }
   }
 
diff --git a/src/apm/events/APMEventListener.ts b/src/apm/events/APMEventListener.ts
index b4447087..3ed57514 100644
--- a/src/apm/events/APMEventListener.ts
+++ b/src/apm/events/APMEventListener.ts
@@ -60,6 +60,15 @@ module ProcessOut {
         paymentState?: string
       }
 
+      // Emitted when a headless redirect auto-open was blocked by the browser (e.g. Safari
+      // popup blocker) and the SDK has surfaced its manual-fallback Pay UI. Fired before
+      // forceUpdate so the merchant can make their container visible first.
+      // `retry` is a bound reference to handleRedirectClick — call it from a real user-gesture
+      // handler (e.g. an onclick) to open the payment tab with a fresh browser gesture.
+      "redirect-popup-blocked": {
+        retry: () => void
+      }
+
       "copy-to-clipboard": {
         text: string
       }
diff --git a/src/apm/references.ts b/src/apm/references.ts
index 3dca5f09..8e6e2ede 100644
--- a/src/apm/references.ts
+++ b/src/apm/references.ts
@@ -34,6 +34,7 @@
 /// <reference path="views/NextSteps.ts" />
 /// <reference path="views/Pending.ts" />
 /// <reference path="views/Redirect.ts" />
+/// <reference path="views/PopupBlockedFallback.ts" />
 /// <reference path="views/CancelRequest.ts" />
 /// <reference path="views/utils/render-elements.ts" />
 /// <reference path="views/utils/form.ts" />
diff --git a/src/apm/views/PopupBlockedFallback.ts b/src/apm/views/PopupBlockedFallback.ts
new file mode 100644
index 00000000..311915ec
--- /dev/null
+++ b/src/apm/views/PopupBlockedFallback.ts
@@ -0,0 +1,76 @@
+module ProcessOut {
+  const { div } = elements
+
+  interface PopupBlockedFallbackProps {
+    config: APIRedirectBase & Partial<PaymentContext>
+    onRetry: () => void
+  }
+
+  /**
+   * Renders the Pay button UI inside the popup-blocked overlay modal.
+   * Used when a headless redirect popup is blocked by the browser — this view
+   * is mounted into a fresh APMPageImpl overlaid on document.body so it is
+   * always visible regardless of the merchant's container visibility.
+   *
+   * Cancel confirmation is handled inline (local state) so it renders inside
+   * the overlay rather than delegating to ContextImpl.context.page, which is
+   * the invisible main container in headless mode.
+   */
+  export class APMViewPopupBlockedFallback extends APMViewImpl<PopupBlockedFallbackProps> {
+    private showingCancelConfirm = false
+
+    private onCancelClick() {
+      ContextImpl.context.events.emit('request-cancel')
+      this.showingCancelConfirm = true
+      this.forceUpdate()
+    }
+
+    private onCancelConfirm() {
+      ContextImpl.context.events.emit('payment-cancelled')
+    }
+
+    private onCancelBack() {
+      this.showingCancelConfirm = false
+      this.forceUpdate()
+    }
+
+    render() {
+      if (this.showingCancelConfirm) {
+        return (
+          Main({
+            config: this.props.config,
+            hideAmount: true,
+            buttons: [
+              Button({ onclick: this.onCancelBack.bind(this) }, 'Back to payment'),
+              Button({ onclick: this.onCancelConfirm.bind(this), variant: 'secondary' }, 'Cancel payment'),
+            ]
+          },
+            div({ className: 'cancel-request' },
+              div({ className: 'cancel-request-message' }, 'Are you sure you want to cancel the payment?')
+            ),
+          )
+        )
+      }
+
+      const redirectLabel = `Pay ${formatCurrency(this.props.config.invoice.amount, this.props.config.invoice.currency)}`
+      return (
+        Main({
+          config: this.props.config,
+          className: 'redirect-page',
+          hideAmount: true,
+          buttons: [
+            Button({ onclick: this.props.onRetry }, redirectLabel),
+            ContextImpl.context.confirmation.allowCancelation
+              ? Button({ onclick: this.onCancelClick.bind(this), variant: 'secondary' }, 'Cancel')
+              : null
+          ]
+        },
+          div({ className: 'heading-container' },
+            Header('Continue to payment'),
+            SubHeader('Click the button below to complete your payment'),
+          )
+        )
+      )
+    }
+  }
+}
diff --git a/src/apm/views/Redirect.ts b/src/apm/views/Redirect.ts
index 310faa62..e8c6c5b5 100644
--- a/src/apm/views/Redirect.ts
+++ b/src/apm/views/Redirect.ts
@@ -9,6 +9,10 @@ module ProcessOut {
     /** After a retryable headless error (e.g. pop-up blocked), show the normal Pay / Cancel UI. */
     private headlessManualFallback = false
 
+    /** Overlay mounted on document.body when popup is blocked in headless mode. */
+    private popupBlockedOverlayEl: HTMLElement | null = null
+    private popupBlockedOverlayPage: APMPageImpl | null = null
+
     styles = css`
       .redirect-headless-loading {
         justify-content: center;
@@ -32,6 +36,44 @@ module ProcessOut {
       }
     }
 
+    private showPopupBlockedFallbackOverlay() {
+      // Full-screen backdrop with centered content card
+      const overlay = document.createElement('div')
+      overlay.style.cssText = 'position:fixed;top:0;left:0;right:0;bottom:0;z-index:2147483647;background:rgba(0,0,0,0.5);display:flex;align-items:center;justify-content:center;padding:16px;box-sizing:border-box;'
+      document.body.appendChild(overlay)
+      this.popupBlockedOverlayEl = overlay
+
+      // Inner wrapper gives APMPageImpl a bounded container to render into
+      const content = document.createElement('div')
+      content.style.cssText = 'width:100%;max-width:400px;'
+      overlay.appendChild(content)
+
+      const overlayPage = new APMPageImpl(content)
+      this.popupBlockedOverlayPage = overlayPage
+
+      overlayPage.render(APMViewPopupBlockedFallback, {
+        config: this.props.config,
+        onRetry: () => {
+          this.removePopupBlockedFallbackOverlay()
+          this.handleRedirectClick()
+        },
+      })
+
+      // Auto-clean up when the payment reaches a terminal state
+      const remove = () => this.removePopupBlockedFallbackOverlay()
+      ContextImpl.context.events.on('success', remove)
+      ContextImpl.context.events.on('failure', remove)
+      ContextImpl.context.events.on('payment-cancelled', remove)
+    }
+
+    private removePopupBlockedFallbackOverlay() {
+      if (this.popupBlockedOverlayEl) {
+        this.popupBlockedOverlayEl.remove()
+        this.popupBlockedOverlayEl = null
+        this.popupBlockedOverlayPage = null
+      }
+    }
+
     handleRedirectClick() {
       ContextImpl.context.events.emit('redirect-initiated')
       const pm = this.props.config.payment_method
@@ -60,7 +102,17 @@ module ProcessOut {
           if (headless) {
             if (!this.headlessManualFallback && failure.code === 'customer.popup-blocked') {
               this.headlessManualFallback = true
-              this.forceUpdate()
+              // popupBlockedOverlay: true (default) → mount SDK Pay button overlay on document.body,
+              //                               always visible regardless of container visibility.
+              // popupBlockedOverlay: false → suppress SDK overlay; merchant handles redirect-popup-blocked.
+              if (!redir || redir.popupBlockedOverlay !== false) {
+                this.showPopupBlockedFallbackOverlay()
+              }
+              // Always emit so merchants can provide their own UI if needed.
+              // retry() must be called from a real user-gesture handler.
+              ContextImpl.context.events.emit('redirect-popup-blocked', {
+                retry: this.handleRedirectClick.bind(this),
+              })
               return
             }
             if (this.headlessManualFallback) {
@@ -97,8 +149,8 @@ module ProcessOut {
 
       const redirectLabel = `Pay ${formatCurrency(this.props.config.invoice.amount, this.props.config.invoice.currency)}`;
       return (
-        Main({ 
-            config: this.props.config, 
+        Main({
+            config: this.props.config,
             className: "redirect-page",
             hideAmount: true,
             buttons: [
diff --git a/src/processout/actionhandler.ts b/src/processout/actionhandler.ts
index 4ddbac8b..4dab547e 100644
--- a/src/processout/actionhandler.ts
+++ b/src/processout/actionhandler.ts
@@ -325,6 +325,16 @@ module ProcessOut {
                 return null;
             }
 
+            // Safari (pattern 2): window.open returns a non-null window that is immediately
+            // closed — treat this as popup-blocked rather than letting the 500ms timer fire
+            // a misleading "customer.canceled" error. Only applies to real popup flows;
+            // MockedIFrameWindow (IFrame/FingerprintIframe) initialises closed as undefined.
+            if ((this.options.flow === ActionFlow.NewTab || this.options.flow === ActionFlow.NewWindow) && newWindow.closed) {
+                error(new Exception("customer.popup-blocked"));
+                refocus();
+                return null;
+            }
+
             // We now want to monitor the payment page
             var timer = setInterval(function() {
                 if (!timer) return;
@@ -335,7 +345,6 @@ module ProcessOut {
                   newWindow.close()
                   error(new Exception("customer.canceled"))
 
-                  // Temporary just to investigate the issue
                   telemetryClient.reportWarning({
                     host: window && window.location ? window.location.host : "",
                     fileName: "actionhandler.ts/ActionHandler.handle.timer",
@@ -357,8 +366,7 @@ module ProcessOut {
                   clearInterval(timer)
                   timer = null
                   error(new Exception("customer.canceled", undefined, { reason: "tab_closed" }))
-                  
-                  // Temporary just to investigate the issue
+
                   telemetryClient.reportWarning({
                     host: window && window.location ? window.location.host : "",
                     fileName: "actionhandler.ts/ActionHandler.handle.cancelf",
@@ -536,7 +544,6 @@ module ProcessOut {
 
                     error(new Exception("customer.canceled"));
 
-                    // Temporary just to investigate the issue
                     telemetryClient.reportWarning({
                       host: window && window.location ? window.location.host : "",
                       fileName: "actionhandler.ts/ActionHandler.listenEvents",