diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0985a88d057..4a96aad8fd3 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,3 +4,4 @@
 - Fixes symbol generation when uploading Unity 6 symbols to Crashlytics. (#7867)
 - Fixed SSR issues in Angular 19 by adding support for default and reqHandler exports. (#8145)
 - Added Angular 19 as supported version. (#8145)
+- Fixed `appdistribution:testers:list` raising an error when a tester is not part of any group. (#8191)
diff --git a/src/appdistribution/types.ts b/src/appdistribution/types.ts
index 6c3db213acc..f90155a4cd2 100644
--- a/src/appdistribution/types.ts
+++ b/src/appdistribution/types.ts
@@ -76,7 +76,7 @@ export interface ListTestersResponse {
 export interface Tester {
   name: string;
   displayName?: string;
-  groups: string[];
+  groups?: string[];
   lastActivityTime: Date;
 }
 
diff --git a/src/commands/appdistribution-testers-list.ts b/src/commands/appdistribution-testers-list.ts
index cf5fce04e57..5481f175d53 100644
--- a/src/commands/appdistribution-testers-list.ts
+++ b/src/commands/appdistribution-testers-list.ts
@@ -47,7 +47,7 @@ function printTestersTable(testers: Tester[]): void {
 
   for (const tester of testers) {
     const name = tester.name.split("/").pop();
-    const groups = tester.groups
+    const groups = (tester.groups ?? [])
       .map((grp) => grp.split("/").pop())
       .sort()
       .join(";");