diff --git a/polygerrit-ui/app/elements/admin/gr-repo-commands/gr-repo-commands.ts b/polygerrit-ui/app/elements/admin/gr-repo-commands/gr-repo-commands.ts
index 13bd13b804..0145b9f6e4 100644
--- a/polygerrit-ui/app/elements/admin/gr-repo-commands/gr-repo-commands.ts
+++ b/polygerrit-ui/app/elements/admin/gr-repo-commands/gr-repo-commands.ts
@@ -128,6 +128,7 @@ export class GrRepoCommands extends GestureEventListeners(
   }
 
   _handleRunningGC() {
+    if (!this.repo) return;
     this._runningGC = true;
     return this.restApiService
       .runRepoGC(this.repo)
diff --git a/polygerrit-ui/app/elements/shared/gr-rest-api-interface/gr-rest-api-interface.ts b/polygerrit-ui/app/elements/shared/gr-rest-api-interface/gr-rest-api-interface.ts
index 38f7780f12..907df349fb 100644
--- a/polygerrit-ui/app/elements/shared/gr-rest-api-interface/gr-rest-api-interface.ts
+++ b/polygerrit-ui/app/elements/shared/gr-rest-api-interface/gr-rest-api-interface.ts
@@ -408,19 +408,7 @@ export class GrRestApiInterface
     }) as Promise<DashboardInfo[] | undefined>;
   }
 
-  saveRepoConfig(repo: RepoName, config: ConfigInput): Promise<Response>;
-
-  saveRepoConfig(
-    repo: RepoName,
-    config: ConfigInput,
-    errFn: ErrorCallback
-  ): Promise<Response | undefined>;
-
-  saveRepoConfig(
-    repo: RepoName,
-    config: ConfigInput,
-    errFn?: ErrorCallback
-  ): Promise<Response | undefined> {
+  saveRepoConfig(repo: RepoName, config: ConfigInput): Promise<Response> {
     // TODO(kaspern): Rename rest api from /projects/ to /repos/ once backend
     // supports it.
     const url = `/projects/${encodeURIComponent(repo)}/config`;
@@ -429,23 +417,11 @@ export class GrRestApiInterface
       method: HttpMethod.PUT,
       url,
       body: config,
-      errFn,
       anonymizedUrl: '/projects/*/config',
     });
   }
 
-  runRepoGC(repo: RepoName): Promise<Response>;
-
-  runRepoGC(
-    repo: RepoName,
-    errFn: ErrorCallback
-  ): Promise<Response | undefined>;
-
-  runRepoGC(repo: RepoName, errFn?: ErrorCallback) {
-    if (!repo) {
-      // TODO(TS): fix return value
-      return '';
-    }
+  runRepoGC(repo: RepoName): Promise<Response> {
     // TODO(kaspern): Rename rest api from /projects/ to /repos/ once backend
     // supports it.
     const encodeName = encodeURIComponent(repo);
@@ -453,7 +429,6 @@ export class GrRestApiInterface
       method: HttpMethod.POST,
       url: `/projects/${encodeName}/gc`,
       body: '',
-      errFn,
       anonymizedUrl: '/projects/*/gc',
     });
   }
diff --git a/polygerrit-ui/app/services/services/gr-rest-api/gr-rest-api.ts b/polygerrit-ui/app/services/services/gr-rest-api/gr-rest-api.ts
index cf064c1148..6d539a9a22 100644
--- a/polygerrit-ui/app/services/services/gr-rest-api/gr-rest-api.ts
+++ b/polygerrit-ui/app/services/services/gr-rest-api/gr-rest-api.ts
@@ -690,10 +690,7 @@ export interface RestApiService {
     includedGroup: GroupId
   ): Promise<Response>;
 
-  runRepoGC(
-    repo: RepoName,
-    errFn?: ErrorCallback
-  ): Promise<Response | undefined>;
+  runRepoGC(repo: RepoName): Promise<Response>;
   getFileContent(
     changeNum: NumericChangeId,
     path: string,