diff --git a/e2e-tests/tests/monitoring/09-deleted-from-server-inventory.yaml b/e2e-tests/tests/monitoring/10-deleted-from-server-inventory.yaml
similarity index 100%
rename from e2e-tests/tests/monitoring/09-deleted-from-server-inventory.yaml
rename to e2e-tests/tests/monitoring/10-deleted-from-server-inventory.yaml
diff --git a/percona/pmm/pmm.go b/percona/pmm/pmm.go
index c4e6b9f4b5..5151479a72 100644
--- a/percona/pmm/pmm.go
+++ b/percona/pmm/pmm.go
@@ -34,6 +34,20 @@ func Container(secret *corev1.Secret, pgc *v2.PerconaPGCluster) (corev1.Containe
 }
 
 // sidecarContainerV2 refers to the construction of the PMM2 container.
+// pmmConfigFile returns the path for the stateless pmm-agent.yaml. From v3.1.0
+// it is placed directly in the writable "/tmp" emptyDir (pmm-agent does not
+// create the config's parent dir, so a subdirectory cannot be used) so PMM
+// works with readOnlyRootFilesystem.
+func pmmConfigFile(pgc *v2.PerconaPGCluster, isPMM3 bool) string {
+	if pgc.CompareVersion("3.1.0") >= 0 {
+		return "/tmp/pmm-agent.yaml"
+	}
+	if isPMM3 {
+		return "/usr/local/percona/pmm/config/pmm-agent.yaml"
+	}
+	return "/usr/local/percona/pmm2/config/pmm-agent.yaml"
+}
+
 func sidecarContainerV2(pgc *v2.PerconaPGCluster) corev1.Container {
 	ports := []corev1.ContainerPort{{ContainerPort: 7777}}
 
@@ -131,7 +145,7 @@ func sidecarContainerV2(pgc *v2.PerconaPGCluster) corev1.Container {
 		},
 		{
 			Name:  "PMM_AGENT_CONFIG_FILE",
-			Value: "/usr/local/percona/pmm2/config/pmm-agent.yaml",
+			Value: pmmConfigFile(pgc, false),
 		},
 		{
 			Name:  "PMM_AGENT_LOG_LEVEL",
@@ -332,7 +346,7 @@ func sidecarContainerV3(pgc *v2.PerconaPGCluster) corev1.Container {
 		},
 		{
 			Name:  "PMM_AGENT_CONFIG_FILE",
-			Value: "/usr/local/percona/pmm/config/pmm-agent.yaml",
+			Value: pmmConfigFile(pgc, true),
 		},
 		{
 			Name:  "PMM_AGENT_LOG_LEVEL",
diff --git a/percona/pmm/pmm_test.go b/percona/pmm/pmm_test.go
index b0459f832a..5fbf6781a0 100644
--- a/percona/pmm/pmm_test.go
+++ b/percona/pmm/pmm_test.go
@@ -141,6 +141,30 @@ func TestContainer(t *testing.T) {
 
 }
 
+func TestPMMConfigFile(t *testing.T) {
+	newPGC := func(crVersion string) *v2.PerconaPGCluster {
+		return &v2.PerconaPGCluster{
+			Spec: v2.PerconaPGClusterSpec{CRVersion: crVersion},
+		}
+	}
+
+	t.Run("v3.1.0 PMM2", func(t *testing.T) {
+		assert.Equal(t, "/tmp/pmm-agent.yaml", pmmConfigFile(newPGC("3.1.0"), false))
+	})
+	t.Run("v3.1.0 PMM3", func(t *testing.T) {
+		assert.Equal(t, "/tmp/pmm-agent.yaml", pmmConfigFile(newPGC("3.1.0"), true))
+	})
+	t.Run("newer than 3.1.0", func(t *testing.T) {
+		assert.Equal(t, "/tmp/pmm-agent.yaml", pmmConfigFile(newPGC("3.2.0"), true))
+	})
+	t.Run("older than 3.1.0 PMM2", func(t *testing.T) {
+		assert.Equal(t, "/usr/local/percona/pmm2/config/pmm-agent.yaml", pmmConfigFile(newPGC("3.0.0"), false))
+	})
+	t.Run("older than 3.1.0 PMM3", func(t *testing.T) {
+		assert.Equal(t, "/usr/local/percona/pmm/config/pmm-agent.yaml", pmmConfigFile(newPGC("3.0.0"), true))
+	})
+}
+
 func TestSidecarContainerV2(t *testing.T) {
 	pmmSpec := &v2.PMMSpec{
 		Image:                    "percona/pmm-client:pmm2-enabled",
@@ -200,7 +224,7 @@ func TestSidecarContainerV2(t *testing.T) {
 		"PMM_AGENT_LISTEN_PORT":            "7777",
 		"PMM_AGENT_PORTS_MIN":              "30100",
 		"PMM_AGENT_PORTS_MAX":              "30105",
-		"PMM_AGENT_CONFIG_FILE":            "/usr/local/percona/pmm2/config/pmm-agent.yaml",
+		"PMM_AGENT_CONFIG_FILE":            "/tmp/pmm-agent.yaml",
 		"PMM_AGENT_LOG_LEVEL":              "info",
 		"PMM_AGENT_DEBUG":                  "false",
 		"PMM_AGENT_TRACE":                  "false",
@@ -309,7 +333,7 @@ func TestSidecarContainerV3(t *testing.T) {
 		"PMM_AGENT_LISTEN_PORT":            "7777",
 		"PMM_AGENT_PORTS_MIN":              "30100",
 		"PMM_AGENT_PORTS_MAX":              "30105",
-		"PMM_AGENT_CONFIG_FILE":            "/usr/local/percona/pmm/config/pmm-agent.yaml",
+		"PMM_AGENT_CONFIG_FILE":            "/tmp/pmm-agent.yaml",
 		"PMM_AGENT_LOG_LEVEL":              "info",
 		"PMM_AGENT_DEBUG":                  "false",
 		"PMM_AGENT_TRACE":                  "false",