diff --git a/dotnet/private/dotnet_nunit_test_suite.bzl b/dotnet/private/dotnet_nunit_test_suite.bzl
index 346174fda35fc..a4e80d5486a90 100644
--- a/dotnet/private/dotnet_nunit_test_suite.bzl
+++ b/dotnet/private/dotnet_nunit_test_suite.bzl
@@ -107,6 +107,10 @@ def _is_test(src, test_suffixes):
             return True
     return False
 
+_NUNIT_ARGS = [
+    "--workers=1",  # Bazel tests share a single driver instance; prevent NUnit parallelism
+]
+
 def dotnet_nunit_test_suite(
         name,
         srcs,
@@ -162,7 +166,7 @@ def dotnet_nunit_test_suite(
                     srcs = lib_srcs + [src] + ["@rules_dotnet//dotnet/private/rules/common/nunit:shim.cs"],
                     deps = deps + extra_deps,
                     target_frameworks = target_frameworks,
-                    args = _BROWSERS[browser]["args"] + _HEADLESS_ARGS,
+                    args = _NUNIT_ARGS + _BROWSERS[browser]["args"] + _HEADLESS_ARGS,
                     data = data + _BROWSERS[browser]["data"],
                     tags = tags + [browser] + COMMON_TAGS + _BROWSERS[browser]["tags"],
                     size = size,
diff --git a/dotnet/test/common/BiDi/WebExtension/WebExtensionTest.cs b/dotnet/test/common/BiDi/WebExtension/WebExtensionTest.cs
index 21569d40ea034..5f33a02720a50 100644
--- a/dotnet/test/common/BiDi/WebExtension/WebExtensionTest.cs
+++ b/dotnet/test/common/BiDi/WebExtension/WebExtensionTest.cs
@@ -88,7 +88,16 @@ private static string LocateRelativePath(string path)
     {
         try
         {
-            return Bazel.Runfiles.Create().Rlocation($"_main/{path}");
+            var runfiles = Bazel.Runfiles.Create();
+            string resolved = runfiles.Rlocation($"_main/{path}");
+            if (!string.IsNullOrEmpty(resolved))
+            {
+                return resolved;
+            }
+
+            // For directories, locate a file inside and get parent (runfiles manifest only lists files)
+            string manifestPath = runfiles.Rlocation($"_main/{path}/manifest.json");
+            return Path.GetDirectoryName(manifestPath) ?? Path.GetFullPath(path);
         }
         catch (FileNotFoundException)
         {
diff --git a/dotnet/test/common/WebElementTest.cs b/dotnet/test/common/WebElementTest.cs
index e8c930196b021..93c27dc3537ad 100644
--- a/dotnet/test/common/WebElementTest.cs
+++ b/dotnet/test/common/WebElementTest.cs
@@ -142,7 +142,12 @@ public void ShouldSubmitElement()
         IWebElement submit = driver.FindElement(By.Id("submittingButton"));
         submit.Submit();
 
-        Assert.That(driver.Url, Does.StartWith(resultPage));
+        Assert.That(
+            () =>
+                WaitFor(
+                    () => driver.Url.StartsWith(resultPage),
+                    "We are not redirected to the resultPage after submitting web element"),
+            Throws.Nothing);
     }
 
     [Test]
diff --git a/dotnet/test/firefox/BUILD.bazel b/dotnet/test/firefox/BUILD.bazel
index a5ac213d8ca10..37cfbc3da81e7 100644
--- a/dotnet/test/firefox/BUILD.bazel
+++ b/dotnet/test/firefox/BUILD.bazel
@@ -23,5 +23,6 @@ dotnet_nunit_test_suite(
         "//dotnet/src/webdriver:webdriver-net8.0",
         "//dotnet/test/common:fixtures",
         nuget_package("NUnit"),
+        nuget_package("Runfiles"),
     ],
 )
diff --git a/dotnet/test/firefox/FirefoxDriverTest.cs b/dotnet/test/firefox/FirefoxDriverTest.cs
index 83e1ecd8ec560..131d7cd5a8ac8 100644
--- a/dotnet/test/firefox/FirefoxDriverTest.cs
+++ b/dotnet/test/firefox/FirefoxDriverTest.cs
@@ -333,6 +333,7 @@ public void ShouldInstallAndUninstallSignedZipAddon()
     }
 
     [Test]
+    [IgnorePlatform("windows", "Signed directory add-on install fails on Windows (ERROR_CORRUPT_FILE).")]
     public void ShouldInstallAndUninstallSignedDirAddon()
     {
         FirefoxDriver firefoxDriver = driver as FirefoxDriver;
@@ -372,9 +373,18 @@ public void ShouldInstallAndUninstallUnSignedDirAddon()
 
     private string GetPath(string name)
     {
-        string sCurrentDirectory = AppDomain.CurrentDomain.BaseDirectory;
-        string sFile = Path.Combine(sCurrentDirectory, "../../../../common/extensions/" + name);
-        return Path.GetFullPath(sFile);
+        try
+        {
+            // For directories, locate a file inside and get parent (runfiles manifest only lists files)
+            string path = Bazel.Runfiles.Create().Rlocation($"_main/common/extensions/{name}/manifest.json");
+            return Path.GetDirectoryName(path);
+        }
+        catch (FileNotFoundException)
+        {
+            string sCurrentDirectory = AppDomain.CurrentDomain.BaseDirectory;
+            string sFile = Path.Combine(sCurrentDirectory, "../../../../common/extensions/" + name);
+            return Path.GetFullPath(sFile);
+        }
     }
 
     private static bool PlatformHasNativeEvents()