diff --git a/frontend/src/components/Initializers/AdditionalInitializers.test.tsx b/frontend/src/components/Initializers/AdditionalInitializers.test.tsx
index 74a909d626..02468d920a 100644
--- a/frontend/src/components/Initializers/AdditionalInitializers.test.tsx
+++ b/frontend/src/components/Initializers/AdditionalInitializers.test.tsx
@@ -174,6 +174,49 @@ describe('AdditionalInitializers', () => {
     expect(within(row).queryByRole('textbox', { name: 'Parameters JSON' })).not.toBeInTheDocument()
   })
 
+  it('should disable Edit while the initializer catalog is unavailable', () => {
+    render(
+      <TestWrapper>
+        <AdditionalInitializers
+          {...defaultProps}
+          registeredInitializers={[]}
+          catalogStatus="error"
+        />
+      </TestWrapper>,
+    )
+
+    const row = screen.getByTestId('initializer-row-additional-1')
+    const editButton = within(row).getByRole('button', { name: 'Edit' })
+    expect(editButton).toBeDisabled()
+    expect(
+      within(row).getByText('Initializer catalog is unavailable. Edit is disabled until the catalog loads.'),
+    ).toBeInTheDocument()
+    // The saved parameters stay visible so operators can still see the stored value.
+    expect(within(row).getByText(/"tags"/)).toBeInTheDocument()
+  })
+
+  it('should disable Edit for a name that is no longer registered', () => {
+    render(
+      <TestWrapper>
+        <AdditionalInitializers
+          {...defaultProps}
+          registeredInitializers={[scorerInitializer]}
+          catalogStatus="loaded"
+        />
+      </TestWrapper>,
+    )
+
+    const row = screen.getByTestId('initializer-row-additional-1')
+    const editButton = within(row).getByRole('button', { name: 'Edit' })
+    expect(editButton).toBeDisabled()
+    // No synthetic catalog entry is rendered: no env vars or parameter summary for the row.
+    expect(within(row).queryByText(/Required env vars:/)).not.toBeInTheDocument()
+    expect(within(row).queryByText(/tags \(list\[str\], optional\)/)).not.toBeInTheDocument()
+    expect(
+      within(row).queryByText('Initializer catalog is unavailable. Edit is disabled until the catalog loads.'),
+    ).not.toBeInTheDocument()
+  })
+
   it('should show the description as hover text on the initializer name', async () => {
     const user = userEvent.setup()
 
diff --git a/frontend/src/components/Initializers/AdditionalInitializers.tsx b/frontend/src/components/Initializers/AdditionalInitializers.tsx
index 992292ca3c..9bb07370bb 100644
--- a/frontend/src/components/Initializers/AdditionalInitializers.tsx
+++ b/frontend/src/components/Initializers/AdditionalInitializers.tsx
@@ -17,7 +17,11 @@ import type {
 import { toApiError } from '@/services/errors'
 import { useAdditionalInitializersStyles } from './AdditionalInitializers.styles'
 import { formatInitializerParameters, formatSupportedParameterSummary } from './initializerFormatting'
-import { resolveRegisteredInitializer } from './initializerLookup'
+import {
+  findRegisteredInitializer,
+  initializerFallbackDescription,
+  type CatalogStatus,
+} from './initializerLookup'
 import InitializerParametersDialog from './InitializerParametersDialog'
 import { useInitializersStyles } from './Initializers.styles'
 import ConfirmDialog from '../ConfirmDialog'
@@ -25,6 +29,7 @@ import ConfirmDialog from '../ConfirmDialog'
 interface AdditionalInitializersProps {
   items: AdditionalInitializerSetting[]
   registeredInitializers: RegisteredInitializer[]
+  catalogStatus?: CatalogStatus
   creating: boolean
   savingInitializerId?: string | null
   saveErrors?: Record<string, string>
@@ -39,7 +44,8 @@ interface AdditionalInitializersProps {
 
 interface AdditionalInitializerCardProps {
   item: AdditionalInitializerSetting
-  initializer: RegisteredInitializer
+  initializer: RegisteredInitializer | undefined
+  catalogStatus: CatalogStatus
   isSaving: boolean
   isApplying: boolean
   isDeleting: boolean
@@ -53,6 +59,7 @@ interface AdditionalInitializerCardProps {
 function AdditionalInitializerCard({
   item,
   initializer,
+  catalogStatus,
   isSaving,
   isApplying,
   isDeleting,
@@ -81,28 +88,45 @@ function AdditionalInitializerCard({
     }
   }
 
+  const canEdit = initializer !== undefined && catalogStatus === 'loaded'
+
   return (
     <div role="listitem" className={styles.card} data-testid={`initializer-row-${item.id}`}>
       <div className={styles.cardHeader}>
         <div className={styles.titleGroup}>
-          <Tooltip content={initializer.description || 'No description available.'} relationship="description" withArrow>
+          <Tooltip
+            content={
+              initializer
+                ? initializer.description || 'No description available.'
+                : initializerFallbackDescription(catalogStatus)
+            }
+            relationship="description"
+            withArrow
+          >
             <Text weight="semibold" size={400}>{item.initializer_name}</Text>
           </Tooltip>
-          {initializer.required_env_vars.length > 0 && (
+          {initializer && initializer.required_env_vars.length > 0 && (
             <Text className={styles.envVarText}>
               Required env vars: {initializer.required_env_vars.join(', ')}
             </Text>
           )}
+          {catalogStatus === 'error' && (
+            <Text size={200} className={styles.envVarText}>
+              Initializer catalog is unavailable. Edit is disabled until the catalog loads.
+            </Text>
+          )}
         </div>
       </div>
 
-      <div className={styles.parameterList}>
-        {formatSupportedParameterSummary(initializer).map((summary: string) => (
-          <Text key={summary} className={styles.parameterHint} size={200}>
-            {summary}
-          </Text>
-        ))}
-      </div>
+      {initializer && (
+        <div className={styles.parameterList}>
+          {formatSupportedParameterSummary(initializer).map((summary: string) => (
+            <Text key={summary} className={styles.parameterHint} size={200}>
+              {summary}
+            </Text>
+          ))}
+        </div>
+      )}
 
       <div>
         <Text weight="semibold" size={300}>Parameters</Text>
@@ -110,7 +134,7 @@ function AdditionalInitializerCard({
       </div>
 
       <div className={styles.actionsRow}>
-        <Button appearance="primary" onClick={() => setEditOpen(true)} disabled={isBusy}>
+        <Button appearance="primary" onClick={() => setEditOpen(true)} disabled={isBusy || !canEdit}>
           Edit
         </Button>
         <Button
@@ -142,7 +166,7 @@ function AdditionalInitializerCard({
         <InitializerParametersDialog
           open
           mode="edit"
-          initializer={initializer}
+          initializer={initializer ?? null}
           initialParameters={item.parameters}
           submitting={isSaving}
           externalError={saveError}
@@ -157,6 +181,7 @@ function AdditionalInitializerCard({
 export default function AdditionalInitializers({
   items,
   registeredInitializers,
+  catalogStatus = 'loaded',
   creating,
   savingInitializerId = null,
   saveErrors = {},
@@ -237,7 +262,8 @@ export default function AdditionalInitializers({
             <AdditionalInitializerCard
               key={`${item.id}:${formatInitializerParameters(item.parameters)}:${item.order_index ?? ''}`}
               item={item}
-              initializer={resolveRegisteredInitializer(item.initializer_name, registeredInitializers)}
+              initializer={findRegisteredInitializer(item.initializer_name, registeredInitializers)}
+              catalogStatus={catalogStatus}
               isSaving={savingInitializerId === item.id}
               isApplying={applyingInitializerId === item.id}
               isDeleting={deletingInitializerId === item.id}
diff --git a/frontend/src/components/Initializers/AvailableInitializersDialog.test.tsx b/frontend/src/components/Initializers/AvailableInitializersDialog.test.tsx
index 8c741d78b6..a673471ac9 100644
--- a/frontend/src/components/Initializers/AvailableInitializersDialog.test.tsx
+++ b/frontend/src/components/Initializers/AvailableInitializersDialog.test.tsx
@@ -74,4 +74,21 @@ describe('AvailableInitializersDialog', () => {
     const dialog = await screen.findByRole('dialog', { hidden: true })
     expect(within(dialog).getByText('No registered initializers were found.')).toBeInTheDocument()
   })
+
+  it('reports the catalog as unavailable instead of an empty registry when the request failed', async () => {
+    const user = userEvent.setup()
+    render(
+      <TestWrapper>
+        <AvailableInitializersDialog registeredInitializers={[]} catalogStatus="error" />
+      </TestWrapper>,
+    )
+
+    await user.click(screen.getByRole('button', { name: /browse available initializers/i }))
+
+    const dialog = await screen.findByRole('dialog', { hidden: true })
+    expect(
+      within(dialog).getByText('Initializer catalog is unavailable. The list cannot be shown until the catalog loads.'),
+    ).toBeInTheDocument()
+    expect(within(dialog).queryByText('No registered initializers were found.')).not.toBeInTheDocument()
+  })
 })
diff --git a/frontend/src/components/Initializers/AvailableInitializersDialog.tsx b/frontend/src/components/Initializers/AvailableInitializersDialog.tsx
index 82255129a9..0e4057efb5 100644
--- a/frontend/src/components/Initializers/AvailableInitializersDialog.tsx
+++ b/frontend/src/components/Initializers/AvailableInitializersDialog.tsx
@@ -16,15 +16,18 @@ import { AppsListRegular } from '@fluentui/react-icons'
 import type { RegisteredInitializer } from '@/types'
 
 import { formatSupportedParameterSummary } from './initializerFormatting'
+import type { CatalogStatus } from './initializerLookup'
 import { useInitializersStyles } from './Initializers.styles'
 
 interface AvailableInitializersDialogProps {
   registeredInitializers: RegisteredInitializer[]
+  catalogStatus?: CatalogStatus
   disabled?: boolean
 }
 
 export default function AvailableInitializersDialog({
   registeredInitializers,
+  catalogStatus = 'loaded',
   disabled = false,
 }: AvailableInitializersDialogProps) {
   const styles = useInitializersStyles()
@@ -50,7 +53,11 @@ export default function AvailableInitializersDialog({
               Every initializer registered with PyRIT. This is a read-only reference of what exists and the
               parameters each one accepts.
             </Text>
-            {registeredInitializers.length === 0 ? (
+            {registeredInitializers.length === 0 && catalogStatus === 'error' ? (
+              <Text className={styles.emptyState}>
+                Initializer catalog is unavailable. The list cannot be shown until the catalog loads.
+              </Text>
+            ) : registeredInitializers.length === 0 ? (
               <Text className={styles.emptyState}>No registered initializers were found.</Text>
             ) : (
               <div className={styles.dialogList} role="list" aria-label="Available initializers">
diff --git a/frontend/src/components/Initializers/BaselineInitializers.test.tsx b/frontend/src/components/Initializers/BaselineInitializers.test.tsx
index e13b780670..71729a236c 100644
--- a/frontend/src/components/Initializers/BaselineInitializers.test.tsx
+++ b/frontend/src/components/Initializers/BaselineInitializers.test.tsx
@@ -63,6 +63,7 @@ describe('BaselineInitializers', () => {
 
     const row = screen.getByTestId('baseline-initializer-row-ghost')
     expect(within(row).getByText('Initializer is no longer registered.')).toBeInTheDocument()
-    expect(within(row).getByText(/Required env vars: None/)).toBeInTheDocument()
+    // No synthetic catalog entry is rendered, so no env-vars line is shown for the row.
+    expect(within(row).queryByText(/Required env vars:/)).not.toBeInTheDocument()
   })
 })
diff --git a/frontend/src/components/Initializers/BaselineInitializers.tsx b/frontend/src/components/Initializers/BaselineInitializers.tsx
index 46910182ff..aa84f2f692 100644
--- a/frontend/src/components/Initializers/BaselineInitializers.tsx
+++ b/frontend/src/components/Initializers/BaselineInitializers.tsx
@@ -3,17 +3,23 @@ import { Text } from '@fluentui/react-components'
 import type { BaselineInitializerSetting, RegisteredInitializer } from '@/types'
 
 import { formatInitializerParameters } from './initializerFormatting'
-import { resolveRegisteredInitializer } from './initializerLookup'
+import {
+  findRegisteredInitializer,
+  initializerFallbackDescription,
+  type CatalogStatus,
+} from './initializerLookup'
 import { useInitializersStyles } from './Initializers.styles'
 
 interface BaselineInitializersProps {
   items: BaselineInitializerSetting[]
   registeredInitializers: RegisteredInitializer[]
+  catalogStatus?: CatalogStatus
 }
 
 export default function BaselineInitializers({
   items,
   registeredInitializers,
+  catalogStatus = 'loaded',
 }: BaselineInitializersProps) {
   const styles = useInitializersStyles()
 
@@ -32,7 +38,7 @@ export default function BaselineInitializers({
       ) : (
         <div className={styles.baselineGroup} role="list" aria-label="Baseline initializers">
           {items.map((item: BaselineInitializerSetting) => {
-            const initializer = resolveRegisteredInitializer(item.initializer_name, registeredInitializers)
+            const initializer = findRegisteredInitializer(item.initializer_name, registeredInitializers)
             return (
               <div
                 key={`${item.initializer_name}:${item.order_index}`}
@@ -43,12 +49,18 @@ export default function BaselineInitializers({
                 <div className={styles.baselineHeader}>
                   <div className={styles.titleGroup}>
                     <Text weight="semibold" size={400}>{item.initializer_name}</Text>
-                    <Text size={300}>{initializer.description || 'No description available.'}</Text>
-                    <Text size={200} className={styles.metadataText}>
-                      Required env vars: {initializer.required_env_vars.length > 0
-                        ? initializer.required_env_vars.join(', ')
-                        : 'None'}
+                    <Text size={300}>
+                      {initializer
+                        ? initializer.description || 'No description available.'
+                        : initializerFallbackDescription(catalogStatus)}
                     </Text>
+                    {initializer && (
+                      <Text size={200} className={styles.metadataText}>
+                        Required env vars: {initializer.required_env_vars.length > 0
+                          ? initializer.required_env_vars.join(', ')
+                          : 'None'}
+                      </Text>
+                    )}
                     <Text size={200} className={styles.metadataText}>Order: {item.order_index}</Text>
                   </div>
                 </div>
diff --git a/frontend/src/components/Initializers/Initializers.test.tsx b/frontend/src/components/Initializers/Initializers.test.tsx
index 3ddc8b6954..ef13299130 100644
--- a/frontend/src/components/Initializers/Initializers.test.tsx
+++ b/frontend/src/components/Initializers/Initializers.test.tsx
@@ -285,6 +285,28 @@ describe('Initializers', () => {
     expect(screen.getByText('Service Unavailable')).toBeInTheDocument()
   })
 
+  it('should drop the loaded catalog and disable Add when a refresh fails after a successful load', async () => {
+    const user = userEvent.setup()
+    renderInitializers()
+
+    const loadedRow = await screen.findByTestId('baseline-initializer-row-target')
+    await waitFor(() => expect(loadedRow).toHaveTextContent('Registers targets.'))
+    expect(loadedRow).toHaveTextContent('Required env vars: AZURE_OPENAI_ENDPOINT')
+    expect(screen.getByRole('button', { name: 'Add initializer' })).toBeEnabled()
+
+    mockedInitializersApi.listRegistered.mockRejectedValueOnce(new Error('Service Unavailable'))
+    await user.click(screen.getByRole('button', { name: 'Refresh' }))
+
+    await waitFor(() => expect(mockedInitializersApi.listRegistered).toHaveBeenCalledTimes(2))
+    const refreshedRow = await screen.findByTestId('baseline-initializer-row-target')
+    await waitFor(() => expect(refreshedRow).toHaveTextContent('Catalog metadata temporarily unavailable.'))
+    expect(refreshedRow).not.toHaveTextContent('Registers targets.')
+    expect(refreshedRow).not.toHaveTextContent('Required env vars')
+    expect(screen.getByRole('button', { name: 'Add initializer' })).toBeDisabled()
+    expect(screen.getByRole('combobox', { name: 'Initializer to add' })).toBeDisabled()
+    expect(screen.getByText('Service Unavailable')).toBeInTheDocument()
+  })
+
   it('should remove an additional initializer and show success feedback', async () => {
     const user = userEvent.setup()
     renderInitializers()
diff --git a/frontend/src/components/Initializers/Initializers.tsx b/frontend/src/components/Initializers/Initializers.tsx
index 55c7547d7f..ddf735166f 100644
--- a/frontend/src/components/Initializers/Initializers.tsx
+++ b/frontend/src/components/Initializers/Initializers.tsx
@@ -10,6 +10,7 @@ import type { InitializerSettingsResponse, RegisteredInitializer, UpdateAddition
 import AdditionalInitializers from './AdditionalInitializers'
 import AvailableInitializersDialog from './AvailableInitializersDialog'
 import BaselineInitializers from './BaselineInitializers'
+import type { CatalogStatus } from './initializerLookup'
 import { useInitializersStyles } from './Initializers.styles'
 
 interface StatusMessage {
@@ -26,6 +27,7 @@ export default function Initializers() {
   const styles = useInitializersStyles()
   const [settings, setSettings] = useState<InitializerSettingsResponse>(EMPTY_SETTINGS)
   const [registeredInitializers, setRegisteredInitializers] = useState<RegisteredInitializer[]>([])
+  const [catalogStatus, setCatalogStatus] = useState<CatalogStatus>('loading')
   const [loading, setLoading] = useState(true)
   const [statusMessage, setStatusMessage] = useState<StatusMessage | null>(null)
   const [refetchCount, setRefetchCount] = useState(0)
@@ -55,7 +57,12 @@ export default function Initializers() {
 
       if (registeredResult.status === 'fulfilled') {
         setRegisteredInitializers(registeredResult.value.items)
+        setCatalogStatus('loaded')
       } else {
+        // Drop the previous catalog: entries left behind would keep rendering stale
+        // descriptions and env vars, and would keep Add enabled off the first stale name.
+        setRegisteredInitializers([])
+        setCatalogStatus('error')
         const catalogError = toApiError(registeredResult.reason).detail
         setStatusMessage((current: StatusMessage | null) =>
           current
@@ -178,7 +185,8 @@ export default function Initializers() {
         <div className={styles.headerActions}>
           <AvailableInitializersDialog
             registeredInitializers={registeredInitializers}
-            disabled={loading}
+            catalogStatus={catalogStatus}
+            disabled={loading || catalogStatus !== 'loaded'}
           />
           <Button
             appearance="subtle"
@@ -207,10 +215,12 @@ export default function Initializers() {
           <BaselineInitializers
             items={settings.baseline}
             registeredInitializers={registeredInitializers}
+            catalogStatus={catalogStatus}
           />
           <AdditionalInitializers
             items={settings.additional}
             registeredInitializers={registeredInitializers}
+            catalogStatus={catalogStatus}
             creating={creating}
             savingInitializerId={savingInitializerId}
             saveErrors={saveErrors}
diff --git a/frontend/src/components/Initializers/initializerLookup.test.ts b/frontend/src/components/Initializers/initializerLookup.test.ts
index cecf5e57bc..13314a80dd 100644
--- a/frontend/src/components/Initializers/initializerLookup.test.ts
+++ b/frontend/src/components/Initializers/initializerLookup.test.ts
@@ -1,6 +1,6 @@
 import type { RegisteredInitializer } from '@/types'
 
-import { resolveRegisteredInitializer } from './initializerLookup'
+import { findRegisteredInitializer, initializerFallbackDescription } from './initializerLookup'
 
 const registered: RegisteredInitializer[] = [
   {
@@ -19,29 +19,36 @@ const registered: RegisteredInitializer[] = [
   },
 ]
 
-describe('resolveRegisteredInitializer', () => {
+describe('findRegisteredInitializer', () => {
   it('returns the matching catalog entry by name', () => {
-    const result = resolveRegisteredInitializer('scorer', registered)
+    const result = findRegisteredInitializer('scorer', registered)
 
     expect(result).toBe(registered[1])
   })
 
-  it('returns an "no longer registered" placeholder when the name is unknown', () => {
-    const result = resolveRegisteredInitializer('ghost', registered)
+  it('returns undefined when the name is not in a loaded catalog', () => {
+    const result = findRegisteredInitializer('ghost', registered)
 
-    expect(result).toEqual({
-      initializer_name: 'ghost',
-      initializer_type: 'UnknownInitializer',
-      description: 'Initializer is no longer registered.',
-      required_env_vars: [],
-      supported_parameters: [],
-    })
+    expect(result).toBeUndefined()
   })
 
-  it('returns a placeholder when the catalog is empty', () => {
-    const result = resolveRegisteredInitializer('target', [])
+  it('returns undefined when the catalog is empty', () => {
+    const result = findRegisteredInitializer('target', [])
 
-    expect(result.initializer_name).toBe('target')
-    expect(result.initializer_type).toBe('UnknownInitializer')
+    expect(result).toBeUndefined()
+  })
+})
+
+describe('initializerFallbackDescription', () => {
+  it('reports a definitive unregistration once the catalog has loaded', () => {
+    expect(initializerFallbackDescription('loaded')).toBe('Initializer is no longer registered.')
+  })
+
+  it('reports a temporary outage when the catalog request failed', () => {
+    expect(initializerFallbackDescription('error')).toBe('Catalog metadata temporarily unavailable.')
+  })
+
+  it('does not claim unregistration while the catalog is still loading', () => {
+    expect(initializerFallbackDescription('loading')).toBe('Catalog metadata temporarily unavailable.')
   })
 })
diff --git a/frontend/src/components/Initializers/initializerLookup.ts b/frontend/src/components/Initializers/initializerLookup.ts
index 73b3d889b1..c59a2935b3 100644
--- a/frontend/src/components/Initializers/initializerLookup.ts
+++ b/frontend/src/components/Initializers/initializerLookup.ts
@@ -1,26 +1,40 @@
 import type { RegisteredInitializer } from '@/types'
 
+/**
+ * Lifecycle of the registered-initializer catalog request.
+ *
+ * `loading` — the initial fetch has not settled yet.
+ * `loaded` — the catalog is the current source of truth; lookups that miss
+ *   genuinely mean "no longer registered".
+ * `error` — the catalog fetch (or latest refresh) failed; entries may be
+ *   stale, so catalog-derived metadata must not be rendered and controls
+ *   that depend on the catalog stay disabled.
+ */
+export type CatalogStatus = 'loading' | 'loaded' | 'error'
+
 /**
  * Resolve a settings entry's `initializer_name` to its catalog definition.
  *
- * Settings reference an initializer by name; the catalog (from `listRegistered`)
- * is the single source of truth for display metadata. When a persisted name is no
- * longer registered, return a placeholder so the row still renders.
+ * Returns `undefined` when the name is not in the catalog; callers branch on
+ * the catalog status to decide whether that means "no longer registered"
+ * (`loaded`) or "metadata unavailable" (`error`/`loading`) instead of
+ * rendering synthetic placeholder entries.
  */
-export function resolveRegisteredInitializer(
+export function findRegisteredInitializer(
   initializerName: string,
   registeredInitializers: RegisteredInitializer[],
-): RegisteredInitializer {
-  const match = registeredInitializers.find((item) => item.initializer_name === initializerName)
-  if (match) {
-    return match
-  }
+): RegisteredInitializer | undefined {
+  return registeredInitializers.find((item) => item.initializer_name === initializerName)
+}
 
-  return {
-    initializer_name: initializerName,
-    initializer_type: 'UnknownInitializer',
-    description: 'Initializer is no longer registered.',
-    required_env_vars: [],
-    supported_parameters: [],
-  }
+/**
+ * Description shown for a row whose initializer has no catalog entry.
+ *
+ * Only a settled, successful catalog load can claim "no longer registered";
+ * any other status means the metadata is simply not known yet.
+ */
+export function initializerFallbackDescription(catalogStatus: CatalogStatus): string {
+  return catalogStatus === 'loaded'
+    ? 'Initializer is no longer registered.'
+    : 'Catalog metadata temporarily unavailable.'
 }