diff --git a/plugins/auth-backend/src/providers/github/provider.ts b/plugins/auth-backend/src/providers/github/provider.ts
index 8462fa1707..fb61a3ae97 100644
--- a/plugins/auth-backend/src/providers/github/provider.ts
+++ b/plugins/auth-backend/src/providers/github/provider.ts
@@ -258,7 +258,7 @@ export type GithubProviderOptions = {
     /**
      * Maps an auth result to a Backstage identity for the user.
      */
-    resolver?: SignInResolver<GithubOAuthResult>;
+    resolver: SignInResolver<GithubOAuthResult>;
   };
 
   /**
diff --git a/plugins/auth-backend/src/providers/gitlab/provider.ts b/plugins/auth-backend/src/providers/gitlab/provider.ts
index 460139562c..b16757470b 100644
--- a/plugins/auth-backend/src/providers/gitlab/provider.ts
+++ b/plugins/auth-backend/src/providers/gitlab/provider.ts
@@ -199,7 +199,7 @@ export type GitlabProviderOptions = {
    * the catalog for a single user entity that has a matching `microsoft.com/email` annotation.
    */
   signIn?: {
-    resolver?: SignInResolver<OAuthResult>;
+    resolver: SignInResolver<OAuthResult>;
   };
 };
 
diff --git a/plugins/auth-backend/src/providers/google/provider.ts b/plugins/auth-backend/src/providers/google/provider.ts
index 14328c9508..7e5a998785 100644
--- a/plugins/auth-backend/src/providers/google/provider.ts
+++ b/plugins/auth-backend/src/providers/google/provider.ts
@@ -215,7 +215,7 @@ export type GoogleProviderOptions = {
     /**
      * Maps an auth result to a Backstage identity for the user.
      */
-    resolver?: SignInResolver<OAuthResult>;
+    resolver: SignInResolver<OAuthResult>;
   };
 };
 
diff --git a/plugins/auth-backend/src/providers/microsoft/provider.ts b/plugins/auth-backend/src/providers/microsoft/provider.ts
index 4888ca22b4..4bc16fdbef 100644
--- a/plugins/auth-backend/src/providers/microsoft/provider.ts
+++ b/plugins/auth-backend/src/providers/microsoft/provider.ts
@@ -234,7 +234,7 @@ export type MicrosoftProviderOptions = {
     /**
      * Maps an auth result to a Backstage identity for the user.
      */
-    resolver?: SignInResolver<OAuthResult>;
+    resolver: SignInResolver<OAuthResult>;
   };
 };
 
diff --git a/plugins/auth-backend/src/providers/oauth2/provider.ts b/plugins/auth-backend/src/providers/oauth2/provider.ts
index c91ec688c3..efe7dbe82b 100644
--- a/plugins/auth-backend/src/providers/oauth2/provider.ts
+++ b/plugins/auth-backend/src/providers/oauth2/provider.ts
@@ -202,7 +202,7 @@ export type OAuth2ProviderOptions = {
   authHandler?: AuthHandler<OAuthResult>;
 
   signIn?: {
-    resolver?: SignInResolver<OAuthResult>;
+    resolver: SignInResolver<OAuthResult>;
   };
 };
 
diff --git a/plugins/auth-backend/src/providers/oidc/provider.ts b/plugins/auth-backend/src/providers/oidc/provider.ts
index f79f726824..f90adb2922 100644
--- a/plugins/auth-backend/src/providers/oidc/provider.ts
+++ b/plugins/auth-backend/src/providers/oidc/provider.ts
@@ -227,7 +227,7 @@ export type OidcProviderOptions = {
   authHandler?: AuthHandler<OidcAuthResult>;
 
   signIn?: {
-    resolver?: SignInResolver<OidcAuthResult>;
+    resolver: SignInResolver<OidcAuthResult>;
   };
 };
 
diff --git a/plugins/auth-backend/src/providers/okta/provider.ts b/plugins/auth-backend/src/providers/okta/provider.ts
index 60c2666200..36f1e00ee2 100644
--- a/plugins/auth-backend/src/providers/okta/provider.ts
+++ b/plugins/auth-backend/src/providers/okta/provider.ts
@@ -237,7 +237,7 @@ export type OktaProviderOptions = {
     /**
      * Maps an auth result to a Backstage identity for the user.
      */
-    resolver?: SignInResolver<OAuthResult>;
+    resolver: SignInResolver<OAuthResult>;
   };
 };
 
diff --git a/plugins/auth-backend/src/providers/saml/provider.ts b/plugins/auth-backend/src/providers/saml/provider.ts
index fd0e5606f4..c7b0896b49 100644
--- a/plugins/auth-backend/src/providers/saml/provider.ts
+++ b/plugins/auth-backend/src/providers/saml/provider.ts
@@ -165,7 +165,7 @@ export type SamlProviderOptions = {
     /**
      * Maps an auth result to a Backstage identity for the user.
      */
-    resolver?: SignInResolver<SamlAuthResult>;
+    resolver: SignInResolver<SamlAuthResult>;
   };
 };