diff --git a/application/controllers/api/frontend/v1/stv/Kontakt.php b/application/controllers/api/frontend/v1/stv/Kontakt.php
index d246a04d9..cd35768f3 100644
--- a/application/controllers/api/frontend/v1/stv/Kontakt.php
+++ b/application/controllers/api/frontend/v1/stv/Kontakt.php
@@ -574,6 +574,19 @@ class Kontakt extends FHCAPI_Controller
 		$person_id = $this->input->post('person_id');
 		$standort_id = $this->input->post('standort_id');
 
+		//check person_id: allow editing only of persons who are no mitarbeiter
+		if($person_id)
+		{
+			$this->load->model('person/Benutzer_model', 'BenutzerModel');
+			$this->BenutzerModel->addJoin('public.tbl_mitarbeiter ma', 'ON (ma.mitarbeiter_uid = public.tbl_benutzer.uid)');
+
+			$result = $this->BenutzerModel->loadWhere([
+				'person_id' => $person_id
+			]);
+			if(hasData($result))
+				return $this->terminateWithError($this->p->t('ui', 'editingMitarbeiterPVonly'), self::ERROR_TYPE_GENERAL);
+		}
+
 		$result = $this->KontaktModel->update(
 			[
 				'kontakt_id' => $kontakt_id
diff --git a/public/js/components/Bootstrap/Modal.js b/public/js/components/Bootstrap/Modal.js
index 0f2504da6..778951c46 100644
--- a/public/js/components/Bootstrap/Modal.js
+++ b/public/js/components/Bootstrap/Modal.js
@@ -103,6 +103,13 @@ export default {
 				keyboard: this.keyboard
 			});
 	},
+	//to avoid pagelocks if more than one instance
+	beforeUnmount() {
+		if (this.modal) {
+			this.modal.dispose();
+			this.modal = null;
+		}
+	},
 	popup(body, options, title, footer) {
 		const BsModal = this,
 			slots = {};
diff --git a/public/js/components/Stv/Studentenverwaltung/Details/Kontakt/Contact.js b/public/js/components/Stv/Studentenverwaltung/Details/Kontakt/Contact.js
index 4bdda4762..f6f884dde 100644
--- a/public/js/components/Stv/Studentenverwaltung/Details/Kontakt/Contact.js
+++ b/public/js/components/Stv/Studentenverwaltung/Details/Kontakt/Contact.js
@@ -263,7 +263,7 @@ export default {
 			this.$refs[modalRef].hide();
 		},
 		reload() {
-			this.$refs.table.reloadTable();
+			this.$refs.table?.reloadTable();
 		},
 		searchFirma(event) {
 			if (this.abortController.firmen) {
diff --git a/public/js/components/Stv/Studentenverwaltung/Details/Projektarbeit/Projektbetreuer.js b/public/js/components/Stv/Studentenverwaltung/Details/Projektarbeit/Projektbetreuer.js
index 8be2d0153..eba03b8f7 100644
--- a/public/js/components/Stv/Studentenverwaltung/Details/Projektarbeit/Projektbetreuer.js
+++ b/public/js/components/Stv/Studentenverwaltung/Details/Projektarbeit/Projektbetreuer.js
@@ -30,6 +30,9 @@ export default {
 	computed: {
 		betreuerFormOpened() {
 			return this.newMode || this.editMode;
+		},
+		isMitarbeiter(){
+			return this.autocompleteSelectedBetreuer?.name?.includes('Mitarbeiter') ?? false;
 		}
 	},
 	props: {
@@ -430,6 +433,11 @@ export default {
 		},
 		actionKontaktdatenBearbeiten() {
 			if (!this.autocompleteSelectedBetreuer) return;
+			if (this.isMitarbeiter)
+			{
+				this.$fhcAlert.alertError(this.$p.t('ui', 'editingMitarbeiterPVonly'));
+				return;
+			} 
 			this.$refs.kontaktdatenModal.show();
 		},
 		// stuff to do after new person has been saved
@@ -494,7 +502,12 @@ export default {
 						<button class="btn btn-outline-secondary" @click="actionNewPerson">{{ $p.t('projektarbeit', 'neuePersonAnlegen') }}</button>
 					</div>
 					<div class="col-6">
-						<button class="btn btn-outline-secondary float-end" @click="actionKontaktdatenBearbeiten">{{ $p.t('projektarbeit', 'kontaktdatenBearbeiten') }}</button>
+						<button
+							class="btn btn-outline-secondary float-end"
+							@click="actionKontaktdatenBearbeiten"
+						>
+							{{ $p.t('projektarbeit', 'kontaktdatenBearbeiten') }}
+						</button>
 					</div>
 				</div>
 
@@ -605,7 +618,7 @@ export default {
 				</contact>
 			</div>
 		</div>
-
 	</bs-modal>
+
 `
 }
diff --git a/system/phrasesupdate.php b/system/phrasesupdate.php
index 11c110f4f..501b5d38e 100644
--- a/system/phrasesupdate.php
+++ b/system/phrasesupdate.php
@@ -63774,6 +63774,26 @@ I have been informed that I am under no obligation to consent to the transmissio
 		)
 	),
 	// ### Infocenter Onboarding END
+	array(
+		'app' => 'core',
+		'category' => 'ui',
+		'phrase' => 'editingMitarbeiterPVonly',
+		'insertvon' => 'system',
+		'phrases' => array(
+			array(
+				'sprache' => 'German',
+				'text' => 'Kontaktdaten von Mitarbeiter*innen dürfen nur in der Personalverwaltung editiert werden.',
+				'description' => '',
+				'insertvon' => 'system'
+			),
+			array(
+				'sprache' => 'English',
+				'text' => 'Employee contact details may only be edited in the personnel administration system.',
+				'description' => '',
+				'insertvon' => 'system'
+			)
+		)
+	),
 	//****************************	 CIS Projektabgabeuebersicht start
 	array(
 		'app' => 'core',