diff --git a/apps/admin-x-settings/src/components/settings/site/theme/InvalidThemeModal.tsx b/apps/admin-x-settings/src/components/settings/site/theme/InvalidThemeModal.tsx
index 8a7b7d7ba9..e827414145 100644
--- a/apps/admin-x-settings/src/components/settings/site/theme/InvalidThemeModal.tsx
+++ b/apps/admin-x-settings/src/components/settings/site/theme/InvalidThemeModal.tsx
@@ -6,7 +6,7 @@ import {ThemeProblem} from '@tryghost/admin-x-framework/api/themes';
 type FatalError = {
     details: {
       errors: ThemeProblem[];
-    };
+    }|string;
   };
 
 export type FatalErrors = FatalError[];
@@ -63,7 +63,15 @@ const InvalidThemeModal: React.FC<{
     if (fatalErrors) {
         warningPrompt = <div className="mt-10">
             <List title="Errors">
-                {fatalErrors?.map(error => error?.details?.errors?.map(err => <ThemeProblemView problem={err} />))}
+                {fatalErrors.map((error) => {
+                    if (typeof error.details === 'object' && error.details.errors && error.details.errors.length > 0) {
+                        return error.details.errors.map(err => <ThemeProblemView problem={err} />);
+                    } else if (typeof error.details === 'string') {
+                        return <ListItem title={error.details} />;
+                    } else {
+                        return null;
+                    }
+                })}
             </List>
         </div>;
     }