diff --git a/cmd/fleetctl/fleetctl/gitops_test.go b/cmd/fleetctl/fleetctl/gitops_test.go
index 901c3c05c02..99791069c2e 100644
--- a/cmd/fleetctl/fleetctl/gitops_test.go
+++ b/cmd/fleetctl/fleetctl/gitops_test.go
@@ -824,12 +824,12 @@ software:
 	t.Setenv("TEST_TEAM_NAME", "All teams")
 	_, err = RunAppNoChecks([]string{"gitops", "-f", tmpFile.Name(), "--dry-run"})
 	require.Error(t, err)
-	assert.Contains(t, err.Error(), `"All teams" is a reserved team name`)
+	assert.Contains(t, err.Error(), `is a reserved fleet name`)
 
 	t.Setenv("TEST_TEAM_NAME", "All TEAMS")
 	_, err = RunAppNoChecks([]string{"gitops", "-f", tmpFile.Name()})
 	require.Error(t, err)
-	assert.Contains(t, err.Error(), `"All teams" is a reserved team name`)
+	assert.Contains(t, err.Error(), `is a reserved fleet name`)
 
 	// Dry run
 	t.Setenv("TEST_TEAM_NAME", teamName)
diff --git a/ee/server/service/teams.go b/ee/server/service/teams.go
index be12d38bdaf..fc56354a1a5 100644
--- a/ee/server/service/teams.go
+++ b/ee/server/service/teams.go
@@ -9,7 +9,6 @@ import (
 	"maps"
 	"net/http"
 	"net/url"
-	"strings"
 
 	"github.com/fleetdm/fleet/v4/pkg/optjson"
 	"github.com/fleetdm/fleet/v4/server"
@@ -84,12 +83,8 @@ func (svc *Service) NewTeam(ctx context.Context, p fleet.TeamPayload) (*fleet.Te
 	if *p.Name == "" {
 		return nil, fleet.NewInvalidArgumentError("name", "may not be empty")
 	}
-	l := strings.ToLower(*p.Name)
-	if l == strings.ToLower(fleet.ReservedNameAllTeams) {
-		return nil, fleet.NewInvalidArgumentError("name", `"All teams" is a reserved team name`)
-	}
-	if l == strings.ToLower(fleet.ReservedNameNoTeam) {
-		return nil, fleet.NewInvalidArgumentError("name", `"No team" is a reserved team name`)
+	if fleet.IsReservedTeamName(*p.Name) {
+		return nil, fleet.NewInvalidArgumentError("name", fmt.Sprintf("%q is a reserved fleet name", *p.Name))
 	}
 	team.Name = *p.Name
 
@@ -152,12 +147,8 @@ func (svc *Service) ModifyTeam(ctx context.Context, teamID uint, payload fleet.T
 		if *payload.Name == "" {
 			return nil, fleet.NewInvalidArgumentError("name", "may not be empty")
 		}
-		l := strings.ToLower(*payload.Name)
-		if l == strings.ToLower(fleet.ReservedNameAllTeams) {
-			return nil, fleet.NewInvalidArgumentError("name", `"All teams" is a reserved team name`)
-		}
-		if l == strings.ToLower(fleet.ReservedNameNoTeam) {
-			return nil, fleet.NewInvalidArgumentError("name", `"No team" is a reserved team name`)
+		if fleet.IsReservedTeamName(*payload.Name) {
+			return nil, fleet.NewInvalidArgumentError("name", fmt.Sprintf("%q is a reserved fleet name", *payload.Name))
 		}
 		team.Name = *payload.Name
 	}
@@ -1051,12 +1042,8 @@ func (svc *Service) ApplyTeamSpecs(ctx context.Context, specs []*fleet.TeamSpec,
 			}
 		}
 
-		l := strings.ToLower(spec.Name)
-		if l == strings.ToLower(fleet.ReservedNameAllTeams) {
-			return nil, fleet.NewInvalidArgumentError("name", `"All teams" is a reserved team name`)
-		}
-		if l == strings.ToLower(fleet.ReservedNameNoTeam) {
-			return nil, fleet.NewInvalidArgumentError("name", `"No team" is a reserved team name`)
+		if fleet.IsReservedTeamName(spec.Name) {
+			return nil, fleet.NewInvalidArgumentError("name", fmt.Sprintf("%q is a reserved fleet name", spec.Name))
 		}
 
 		var team *fleet.Team
diff --git a/frontend/pages/admin/TeamManagementPage/TeamManagementPage.tsx b/frontend/pages/admin/TeamManagementPage/TeamManagementPage.tsx
index 7db23489eef..104e7fb36b1 100644
--- a/frontend/pages/admin/TeamManagementPage/TeamManagementPage.tsx
+++ b/frontend/pages/admin/TeamManagementPage/TeamManagementPage.tsx
@@ -119,17 +119,19 @@ const TeamManagementPage = (): JSX.Element => {
           refetchTeams();
         })
         .catch((createError: { data: IApiError }) => {
-          if (createError.data.errors[0].reason.includes("Duplicate")) {
+          const errMsg = createError.data.errors[0].reason.toLowerCase();
+          if (errMsg.includes("duplicate")) {
             setBackendValidators({
               name: "A fleet with this name already exists",
             });
-          } else if (createError.data.errors[0].reason.includes("All teams")) {
+          } else if (
+            errMsg.includes("all teams") ||
+            errMsg.includes("all fleets") ||
+            errMsg.includes("no team") ||
+            errMsg.includes("unassigned")
+          ) {
             setBackendValidators({
-              name: `"All fleets" is a reserved fleet name. Please try another name.`,
-            });
-          } else if (createError.data.errors[0].reason.includes("No team")) {
-            setBackendValidators({
-              name: `"Unassigned" is a reserved fleet name. Please try another name.`,
+              name: `"${formData.name}" is a reserved fleet name. Please try another name.`,
             });
           } else {
             renderFlash("error", "Could not create fleet. Please try again.");
diff --git a/server/fleet/teams.go b/server/fleet/teams.go
index dd10cce715e..61103fe4c49 100644
--- a/server/fleet/teams.go
+++ b/server/fleet/teams.go
@@ -4,6 +4,7 @@ import (
 	"database/sql/driver"
 	"encoding/json"
 	"fmt"
+	"strings"
 	"time"
 
 	"github.com/fleetdm/fleet/v4/pkg/optjson"
@@ -27,10 +28,19 @@ const (
 	ReservedNameNoTeam   = "No team"
 )
 
-// IsReservedTeamName checks if the name provided is a reserved team name
+// Display names used in user-facing error messages.
+const (
+	DisplayNameNoTeam   = "Unassigned"
+	DisplayNameAllTeams = "All fleets"
+)
+
+// IsReservedTeamName checks if the name provided is a reserved fleet name (case-insensitive).
+// Both old names ("No team", "All teams") and new display names ("Unassigned", "All fleets")
+// are reserved to prevent creating teams with any of these names.
 func IsReservedTeamName(name string) bool {
-	normalizedName := norm.NFC.String(name)
-	return normalizedName == ReservedNameAllTeams || normalizedName == ReservedNameNoTeam
+	normalizedName := strings.ToLower(norm.NFC.String(name))
+	return normalizedName == "no team" || normalizedName == "all teams" ||
+		normalizedName == "unassigned" || normalizedName == "all fleets"
 }
 
 type TeamPayload struct {
diff --git a/server/service/integration_enterprise_test.go b/server/service/integration_enterprise_test.go
index 290cd5eb944..4c4578b384c 100644
--- a/server/service/integration_enterprise_test.go
+++ b/server/service/integration_enterprise_test.go
@@ -1671,11 +1671,11 @@ func (s *integrationEnterpriseTestSuite) TestTeamEndpoints() {
 	}
 
 	r := s.Do("POST", "/api/latest/fleet/teams", teamReserved, http.StatusUnprocessableEntity)
-	require.Contains(t, extractServerErrorText(r.Body), `"No team" is a reserved team name`)
+	require.Contains(t, extractServerErrorText(r.Body), `is a reserved fleet name`)
 
 	teamReserved.Name = "AlL TeaMS"
 	r = s.Do("POST", "/api/latest/fleet/teams", teamReserved, http.StatusUnprocessableEntity)
-	require.Contains(t, extractServerErrorText(r.Body), `"All teams" is a reserved team name`)
+	require.Contains(t, extractServerErrorText(r.Body), `is a reserved fleet name`)
 
 	// create a team with too many secrets
 	team3 := &fleet.Team{
@@ -1778,10 +1778,10 @@ func (s *integrationEnterpriseTestSuite) TestTeamEndpoints() {
 
 	// try to rename to reserved names
 	r = s.Do("PATCH", fmt.Sprintf("/api/latest/fleet/teams/%d", tm1ID), fleet.TeamPayload{Name: ptr.String("no TEAM")}, http.StatusUnprocessableEntity)
-	require.Contains(t, extractServerErrorText(r.Body), `"No team" is a reserved team name`)
+	require.Contains(t, extractServerErrorText(r.Body), `is a reserved fleet name`)
 
 	r = s.Do("PATCH", fmt.Sprintf("/api/latest/fleet/teams/%d", tm1ID), fleet.TeamPayload{Name: ptr.String("ALL teAMs")}, http.StatusUnprocessableEntity)
-	require.Contains(t, extractServerErrorText(r.Body), `"All teams" is a reserved team name`)
+	require.Contains(t, extractServerErrorText(r.Body), `is a reserved fleet name`)
 
 	// Modify team's calendar config
 	modifyCalendar := fleet.TeamPayload{