diff --git a/src/SignalR/clients/ts/FunctionalTests/Startup.cs b/src/SignalR/clients/ts/FunctionalTests/Startup.cs
index 45d3f8546a71..dd3ee9378458 100644
--- a/src/SignalR/clients/ts/FunctionalTests/Startup.cs
+++ b/src/SignalR/clients/ts/FunctionalTests/Startup.cs
@@ -184,9 +184,11 @@ public void Configure(IApplicationBuilder app, IWebHostEnvironment env, ILogger<
                 {
                     cookieOptions.SameSite = Microsoft.AspNetCore.Http.SameSiteMode.None;
                     cookieOptions.Secure = true;
+                    cookieOptions.Extensions.Add("partitioned"); // Required by Chromium
 
                     expiredCookieOptions.SameSite = Microsoft.AspNetCore.Http.SameSiteMode.None;
                     expiredCookieOptions.Secure = true;
+                    expiredCookieOptions.Extensions.Add("partitioned"); // Required by Chromium
                 }
                 context.Response.Cookies.Append("testCookie", "testValue", cookieOptions);
                 context.Response.Cookies.Append("testCookie2", "testValue2", cookieOptions);