diff --git a/backend/src/services/customerAccountsService.js b/backend/src/services/customerAccountsService.js
index e6a9567a..bcc0e6fe 100644
--- a/backend/src/services/customerAccountsService.js
+++ b/backend/src/services/customerAccountsService.js
@@ -126,7 +126,16 @@ async function createInvitation({ email, invitedById, prefill }) {
     .first();
   if (existingCustomer && existingCustomer.password_hash) {
     // Already-active customer with this email — duplicate, reject.
-    throw new ConflictError('A customer account with this email already exists', 'email');
+    //
+    // Carries the same code the send-invite route uses for its own
+    // already-active check (#1261). Both conflicts are 409 and both can mean
+    // "this address already has portal access" — the route reads the customer
+    // before this recheck runs, so an invitation accepted in between lands
+    // here instead — and a caller that cannot tell the two apart ends up
+    // telling the admin to cancel an invitation acceptance already closed.
+    const err = new ConflictError('A customer account with this email already exists', 'email');
+    err.code = 'CUSTOMER_ALREADY_ACTIVE';
+    throw err;
   }
   // If the existing customer is PASSIVE (password_hash IS NULL), this
   // is the "promote to active" path: the admin clicked "Send portal
@@ -139,7 +148,9 @@ async function createInvitation({ email, invitedById, prefill }) {
     .where('expires_at', '>', new Date())
     .first();
   if (pendingInvite) {
-    throw new ConflictError('A pending invitation already exists for this email', 'email');
+    const err = new ConflictError('A pending invitation already exists for this email', 'email');
+    err.code = 'INVITATION_ALREADY_PENDING';
+    throw err;
   }
 
   // 64-char hex = 32 bytes = 256 bits of entropy. Same as admin invites.
diff --git a/frontend/src/components/admin/InlineCustomerCreate.tsx b/frontend/src/components/admin/InlineCustomerCreate.tsx
index fc012449..7bc4f4f8 100644
--- a/frontend/src/components/admin/InlineCustomerCreate.tsx
+++ b/frontend/src/components/admin/InlineCustomerCreate.tsx
@@ -189,31 +189,36 @@ export const InlineCustomerCreate: React.FC<Props> = ({ onCreated, onCancel, mod
           toast.success(t('customers.create.savedActiveToast',
             'Customer created and portal invitation queued. It is sent by the email queue — check System health if it does not arrive.'));
         } catch (err: any) {
-          // Three different things reach this branch and they need three
-          // different answers. Only one of them means "no invitation exists".
+          // Four different things reach this branch and they need four
+          // different answers. Only ONE of them means "nothing happened, go
+          // ahead and retry" — every other message that says so sends the
+          // admin into a retry that then 409s.
           const status = err?.response?.status;
           const code = err?.response?.data?.code;
 
-          if (status === 409 && code === 'CUSTOMER_ALREADY_ACTIVE') {
-            // An open invitation for this address was accepted between
-            // createDirect and sendInvite. The customer has portal access
-            // already, so there is nothing to cancel and nothing to resend.
+          if (code === 'CUSTOMER_ALREADY_ACTIVE') {
+            // This address already has portal access — either the route's own
+            // check, or an invitation accepted between it and the service's
+            // recheck. Nothing to cancel, nothing to resend.
             toast.info(t('customers.create.inviteAlreadyActiveToast',
               'Customer saved. This address already has portal access, so no invitation was needed.'));
           } else if (status === 409) {
             // An invitation for this address is already open and the RE-invite
-            // was refused. The customer IS invited; telling them to retry
-            // would send them the wrong way.
+            // was refused. The customer IS invited.
             toast.warn(t('customers.create.inviteAlreadyPendingToast',
               'Customer saved. An invitation for this address is already open — cancel it on the Invitations tab before sending a new one.'));
-          } else if (!err?.response) {
-            // No response at all: a dropped connection or a timeout. The
-            // request may well have succeeded server-side, so claiming it
-            // failed sends the admin into a retry that then 409s. Say what is
-            // actually known and point at where the answer is.
+          } else if (!err?.response || status >= 500) {
+            // No response (dropped connection, timeout) or a server error.
+            // Neither says the invitation was not created: createInvitation
+            // inserts the customer_invitations row and only then queues the
+            // email, without a transaction, so a 500 out of the queueing step
+            // leaves an open invitation behind. Asserting a clean failure here
+            // sends the admin into a retry that 409s and still queues nothing.
             toast.warn(t('customers.create.inviteUnconfirmedToast',
-              'Customer saved, but the invitation could not be confirmed — the server did not answer. Check the Invitations tab before sending another.'));
+              'Customer saved, but the invitation could not be confirmed — check the Invitations tab before sending another.'));
           } else {
+            // A 4xx that is not a conflict: validation, permissions, no such
+            // customer. The request was rejected before anything was written.
             toast.warn(t('customers.create.inviteFailedToast',
               'Customer saved as PASSIVE — no invitation went out. Retry "Send portal invitation" from the customer detail page.'));
           }
diff --git a/frontend/src/i18n/locales/de.json b/frontend/src/i18n/locales/de.json
index 7926a35b..52202aa0 100644
--- a/frontend/src/i18n/locales/de.json
+++ b/frontend/src/i18n/locales/de.json
@@ -4854,7 +4854,7 @@
       "nameRequired": "Geben Sie mindestens einen Firmennamen oder einen Ansprechpartner an.",
       "inviteAlreadyPendingToast": "Kunde gespeichert. Für diese Adresse ist bereits eine Einladung offen — stornieren Sie sie im Tab „Einladungen“, bevor Sie eine neue senden.",
       "inviteAlreadyActiveToast": "Kunde gespeichert. Diese Adresse hat bereits Portalzugang, eine Einladung war nicht nötig.",
-      "inviteUnconfirmedToast": "Kunde gespeichert, aber die Einladung ist unbestätigt — der Server hat nicht geantwortet. Prüfen Sie den Tab „Einladungen“, bevor Sie erneut senden."
+      "inviteUnconfirmedToast": "Kunde gespeichert, aber die Einladung ist unbestätigt — prüfen Sie den Tab „Einladungen“, bevor Sie erneut senden."
     },
     "passive": {
       "badge": "Passiv — nur Admin",
diff --git a/frontend/src/i18n/locales/en.json b/frontend/src/i18n/locales/en.json
index c7fcab28..9a99a02f 100644
--- a/frontend/src/i18n/locales/en.json
+++ b/frontend/src/i18n/locales/en.json
@@ -4854,7 +4854,7 @@
       "nameRequired": "Enter at least a company name or a contact name.",
       "inviteAlreadyPendingToast": "Customer saved. An invitation for this address is already open — cancel it on the Invitations tab before sending a new one.",
       "inviteAlreadyActiveToast": "Customer saved. This address already has portal access, so no invitation was needed.",
-      "inviteUnconfirmedToast": "Customer saved, but the invitation could not be confirmed — the server did not answer. Check the Invitations tab before sending another."
+      "inviteUnconfirmedToast": "Customer saved, but the invitation could not be confirmed — check the Invitations tab before sending another."
     },
     "passive": {
       "badge": "Passive — admin only",
diff --git a/frontend/src/pages/admin/__tests__/customerInvitationVisibility.test.tsx b/frontend/src/pages/admin/__tests__/customerInvitationVisibility.test.tsx
index a52dcfae..ab36e30f 100644
--- a/frontend/src/pages/admin/__tests__/customerInvitationVisibility.test.tsx
+++ b/frontend/src/pages/admin/__tests__/customerInvitationVisibility.test.tsx
@@ -165,9 +165,12 @@ describe('InlineCustomerCreate — what the toast may claim (#1261)', () => {
     expect(message).not.toMatch(/invitation sent/i);
   });
 
-  it('says the customer is PASSIVE when the invitation call failed', async () => {
+  it('says the customer is PASSIVE when the invitation was cleanly rejected', async () => {
+    // A 400 is the shape where "no invitation went out, retry" is true: the
+    // request never got as far as writing anything. Round 2 moved 5xx out of
+    // this branch, because a 500 can leave an invitation row behind.
     createDirect.mockResolvedValue({ id: 6, email: 'new@example.com' });
-    sendInvite.mockRejectedValue({ response: { status: 500 } });
+    sendInvite.mockRejectedValue({ response: { status: 400, data: {} } });
 
     renderWith(<InlineCustomerCreate mode="invite" onCreated={() => {}} onCancel={() => {}} />);
     await fill();
@@ -213,6 +216,57 @@ describe('InlineCustomerCreate — what the toast may claim (#1261)', () => {
     expect(toastWarn).not.toHaveBeenCalled();
   });
 
+  it('stays indeterminate on a 5xx — the invitation row may already exist', async () => {
+    // Codex review round 2. createInvitation inserts customer_invitations and
+    // only then queues the email, with no transaction around the pair, so a
+    // 500 out of the queueing step leaves an open invitation behind. Telling
+    // the admin to retry sends them into a 409 that still queues nothing.
+    createDirect.mockResolvedValue({ id: 11, email: 'new@example.com' });
+    sendInvite.mockRejectedValue({ response: { status: 500, data: {} } });
+
+    renderWith(<InlineCustomerCreate mode="invite" onCreated={() => {}} onCancel={() => {}} />);
+    await fill();
+    await userEvent.click(screen.getByRole('button', { name: /Save & send portal invitation/i }));
+
+    await waitFor(() => expect(toastWarn).toHaveBeenCalled());
+    const message = String(toastWarn.mock.calls[0][0]);
+    expect(message).toMatch(/could not be confirmed/i);
+    expect(message).not.toMatch(/PASSIVE/);
+  });
+
+  it('still calls a plain 4xx a clean failure, where retrying is right', async () => {
+    // The one case where "nothing happened, go ahead and retry" is true: the
+    // request was rejected before anything was written.
+    createDirect.mockResolvedValue({ id: 12, email: 'new@example.com' });
+    sendInvite.mockRejectedValue({ response: { status: 403, data: {} } });
+
+    renderWith(<InlineCustomerCreate mode="invite" onCreated={() => {}} onCancel={() => {}} />);
+    await fill();
+    await userEvent.click(screen.getByRole('button', { name: /Save & send portal invitation/i }));
+
+    await waitFor(() => expect(toastWarn).toHaveBeenCalled());
+    expect(String(toastWarn.mock.calls[0][0])).toMatch(/PASSIVE/);
+  });
+
+  it('reads the service-level already-active 409, not just the route-level one', async () => {
+    // Codex review round 2. createInvitation's own recheck throws
+    // ConflictError, which used to serialise as code CONFLICT — indistinguishable
+    // from the pending-invitation conflict, so the admin was told to cancel an
+    // invitation that acceptance had already closed. The service now labels it.
+    createDirect.mockResolvedValue({ id: 13, email: 'new@example.com' });
+    sendInvite.mockRejectedValue({
+      response: { status: 409, data: { code: 'CUSTOMER_ALREADY_ACTIVE', error: 'A customer account with this email already exists' } },
+    });
+
+    renderWith(<InlineCustomerCreate mode="invite" onCreated={() => {}} onCancel={() => {}} />);
+    await fill();
+    await userEvent.click(screen.getByRole('button', { name: /Save & send portal invitation/i }));
+
+    await waitFor(() => expect(toastInfo).toHaveBeenCalled());
+    expect(String(toastInfo.mock.calls[0][0])).toMatch(/already has portal access/i);
+    expect(toastWarn).not.toHaveBeenCalled();
+  });
+
   it('stays indeterminate when the server never answered', async () => {
     // Codex review round 1. A dropped connection or timeout rejects with no
     // `response`, but the request may have succeeded server-side. Declaring