diff --git a/models/user.go b/models/user.go
index b234ed6cc8c..51ee740c8d3 100644
--- a/models/user.go
+++ b/models/user.go
@@ -13,6 +13,7 @@ import (
 	_ "image/jpeg" // Needed for jpeg support
 
 	asymkey_model "code.gitea.io/gitea/models/asymkey"
+	auth_model "code.gitea.io/gitea/models/auth"
 	"code.gitea.io/gitea/models/db"
 	repo_model "code.gitea.io/gitea/models/repo"
 	user_model "code.gitea.io/gitea/models/user"
@@ -83,6 +84,11 @@ func DeleteUser(ctx context.Context, u *user_model.User) (err error) {
 	}
 	// ***** END: Follow *****
 
+	if _, err := db.GetEngine(ctx).In("grant_id", builder.Select("id").From("oauth2_grant").Where(builder.Eq{"oauth2_grant.user_id": u.ID})).
+		Delete(&auth_model.OAuth2AuthorizationCode{}); err != nil {
+		return err
+	}
+
 	if err = deleteBeans(e,
 		&AccessToken{UID: u.ID},
 		&Collaboration{UserID: u.ID},
@@ -100,6 +106,8 @@ func DeleteUser(ctx context.Context, u *user_model.User) (err error) {
 		&Collaboration{UserID: u.ID},
 		&Stopwatch{UserID: u.ID},
 		&user_model.Setting{UserID: u.ID},
+		&auth_model.OAuth2Application{UID: u.ID},
+		&auth_model.OAuth2Grant{UserID: u.ID},
 	); err != nil {
 		return fmt.Errorf("deleteBeans: %v", err)
 	}
diff --git a/modules/doctor/dbconsistency.go b/modules/doctor/dbconsistency.go
index a7c8312e071..53c988897cd 100644
--- a/modules/doctor/dbconsistency.go
+++ b/modules/doctor/dbconsistency.go
@@ -186,6 +186,15 @@ func checkDBConsistency(logger log.Logger, autofix bool) error {
 		// find action without repository
 		genericOrphanCheck("Action entries without existing repository",
 			"action", "repository", "action.repo_id=repository.id"),
+		// find OAuth2Grant without existing user
+		genericOrphanCheck("Orphaned OAuth2Grant without existing User",
+			"oauth2_grant", "user", "oauth2_grant.user_id=user.id"),
+		// find OAuth2Application without existing user
+		genericOrphanCheck("Orphaned OAuth2Application without existing User",
+			"oauth2_application", "user", "oauth2_application.uid=user.id"),
+		// find OAuth2AuthorizationCode without existing OAuth2Grant
+		genericOrphanCheck("Orphaned OAuth2AuthorizationCode without existing OAuth2Grant",
+			"oauth2_authorization_code", "oauth2_grant", "oauth2_authorization_code.grant_id=oauth2_grant.id"),
 	)
 
 	for _, c := range consistencyChecks {