diff --git a/ipn/ipnlocal/profiles.go b/ipn/ipnlocal/profiles.go
index 1c16ee30b..8cdedad7c 100644
--- a/ipn/ipnlocal/profiles.go
+++ b/ipn/ipnlocal/profiles.go
@@ -22,6 +22,8 @@
 	"tailscale.com/util/winutil"
 )
 
+var errAlreadyMigrated = errors.New("profile migration already completed")
+
 // profileManager is a wrapper around a StateStore that manages
 // multiple profiles and the current profile.
 type profileManager struct {
@@ -66,7 +68,7 @@ func (pm *profileManager) SetCurrentUserID(uid ipn.WindowsUserID) error {
 	b, err := pm.store.ReadState(ipn.CurrentProfileKey(string(uid)))
 	if err == ipn.ErrStateNotExist || len(b) == 0 {
 		if runtime.GOOS == "windows" {
-			if err := pm.migrateFromLegacyPrefs(); err != nil {
+			if err := pm.migrateFromLegacyPrefs(); err != nil && !errors.Is(err, errAlreadyMigrated) {
 				return err
 			}
 		} else {
@@ -544,7 +546,14 @@ func newProfileManagerWithGOOS(store ipn.StateStore, logf logger.Logf, goos stri
 		if err := pm.setPrefsLocked(prefs); err != nil {
 			return nil, err
 		}
-	} else if len(knownProfiles) == 0 && goos != "windows" {
+		// Most platform behavior is controlled by the goos parameter, however
+		// some behavior is implied by build tag and fails when run on Windows,
+		// so we explicitly avoid that behavior when running on Windows.
+		// Specifically this reaches down into legacy preference loading that is
+		// specialized by profiles_windows.go and fails in tests on an invalid
+		// uid passed in from the unix tests. The uid's used for Windows tests
+		// and runtime must be valid Windows security identifier structures.
+	} else if len(knownProfiles) == 0 && goos != "windows" && runtime.GOOS != "windows" {
 		// No known profiles, try a migration.
 		if err := pm.migrateFromLegacyPrefs(); err != nil {
 			return nil, err
@@ -562,7 +571,7 @@ func (pm *profileManager) migrateFromLegacyPrefs() error {
 	sentinel, prefs, err := pm.loadLegacyPrefs()
 	if err != nil {
 		metricMigrationError.Add(1)
-		return err
+		return fmt.Errorf("load legacy prefs: %w", err)
 	}
 	if err := pm.SetPrefs(prefs); err != nil {
 		metricMigrationError.Add(1)
diff --git a/ipn/ipnlocal/profiles_test.go b/ipn/ipnlocal/profiles_test.go
index f3027c3a8..7090b8a0f 100644
--- a/ipn/ipnlocal/profiles_test.go
+++ b/ipn/ipnlocal/profiles_test.go
@@ -5,7 +5,7 @@
 
 import (
 	"fmt"
-	"runtime"
+	"os/user"
 	"strconv"
 	"testing"
 
@@ -18,9 +18,6 @@
 )
 
 func TestProfileCurrentUserSwitch(t *testing.T) {
-	if runtime.GOOS == "windows" {
-		t.Skip("TODO(#7876): test regressed on windows while CI was broken")
-	}
 	store := new(mem.Store)
 
 	pm, err := newProfileManagerWithGOOS(store, logger.Discard, "linux")
@@ -77,9 +74,6 @@ func TestProfileCurrentUserSwitch(t *testing.T) {
 }
 
 func TestProfileList(t *testing.T) {
-	if runtime.GOOS == "windows" {
-		t.Skip("TODO(#7876): test regressed on windows while CI was broken")
-	}
 	store := new(mem.Store)
 
 	pm, err := newProfileManagerWithGOOS(store, logger.Discard, "linux")
@@ -158,9 +152,6 @@ func TestProfileList(t *testing.T) {
 
 // TestProfileManagement tests creating, loading, and switching profiles.
 func TestProfileManagement(t *testing.T) {
-	if runtime.GOOS == "windows" {
-		t.Skip("TODO(#7876): test regressed on windows while CI was broken")
-	}
 	store := new(mem.Store)
 
 	pm, err := newProfileManagerWithGOOS(store, logger.Discard, "linux")
@@ -312,10 +303,11 @@ func TestProfileManagement(t *testing.T) {
 // TestProfileManagementWindows tests going into and out of Unattended mode on
 // Windows.
 func TestProfileManagementWindows(t *testing.T) {
-
-	if runtime.GOOS == "windows" {
-		t.Skip("TODO(#7876): test regressed on windows while CI was broken")
+	u, err := user.Current()
+	if err != nil {
+		t.Fatal(err)
 	}
+	uid := ipn.WindowsUserID(u.Uid)
 
 	store := new(mem.Store)
 
@@ -365,8 +357,8 @@ func TestProfileManagementWindows(t *testing.T) {
 
 	{
 		t.Logf("Set user1 as logged in user")
-		if err := pm.SetCurrentUserID("user1"); err != nil {
-			t.Fatal(err)
+		if err := pm.SetCurrentUserID(uid); err != nil {
+			t.Fatalf("can't set user id: %s", err)
 		}
 		checkProfiles(t)
 		t.Logf("Save prefs for user1")
@@ -401,7 +393,7 @@ func TestProfileManagementWindows(t *testing.T) {
 
 	{
 		t.Logf("Set user1 as current user")
-		if err := pm.SetCurrentUserID("user1"); err != nil {
+		if err := pm.SetCurrentUserID(uid); err != nil {
 			t.Fatal(err)
 		}
 		wantCurProfile = "test"
@@ -411,8 +403,8 @@ func TestProfileManagementWindows(t *testing.T) {
 		t.Logf("set unattended mode")
 		wantProfiles["test"] = setPrefs(t, "test", true)
 	}
-	if pm.CurrentUserID() != "user1" {
-		t.Fatalf("CurrentUserID = %q; want %q", pm.CurrentUserID(), "user1")
+	if pm.CurrentUserID() != uid {
+		t.Fatalf("CurrentUserID = %q; want %q", pm.CurrentUserID(), uid)
 	}
 
 	// Recreate the profile manager to ensure that it starts with test profile.
@@ -421,7 +413,7 @@ func TestProfileManagementWindows(t *testing.T) {
 		t.Fatal(err)
 	}
 	checkProfiles(t)
-	if pm.CurrentUserID() != "user1" {
-		t.Fatalf("CurrentUserID = %q; want %q", pm.CurrentUserID(), "user1")
+	if pm.CurrentUserID() != uid {
+		t.Fatalf("CurrentUserID = %q; want %q", pm.CurrentUserID(), uid)
 	}
 }
diff --git a/ipn/ipnlocal/profiles_windows.go b/ipn/ipnlocal/profiles_windows.go
index bc47e154e..1661c08d3 100644
--- a/ipn/ipnlocal/profiles_windows.go
+++ b/ipn/ipnlocal/profiles_windows.go
@@ -6,6 +6,7 @@
 import (
 	"errors"
 	"fmt"
+	"io/fs"
 	"os"
 	"os/user"
 	"path/filepath"
@@ -21,8 +22,6 @@
 	legacyPrefsExt                   = ".conf"
 )
 
-var errAlreadyMigrated = errors.New("profile migration already completed")
-
 func legacyPrefsDir(uid ipn.WindowsUserID) (string, error) {
 	// TODO(aaron): Ideally we'd have the impersonation token for the pipe's
 	// client and use it to call SHGetKnownFolderPath, thus yielding the correct
@@ -56,6 +55,9 @@ func (pm *profileManager) loadLegacyPrefs() (string, ipn.PrefsView, error) {
 
 	prefsPath := filepath.Join(userLegacyPrefsDir, legacyPrefsFile+legacyPrefsExt)
 	prefs, err := ipn.LoadPrefs(prefsPath)
+	if errors.Is(err, fs.ErrNotExist) {
+		return "", ipn.PrefsView{}, errAlreadyMigrated
+	}
 	if err != nil {
 		return "", ipn.PrefsView{}, err
 	}