diff --git a/lam/HISTORY b/lam/HISTORY
index 82d941e80..cc5dff57b 100644
--- a/lam/HISTORY
+++ b/lam/HISTORY
@@ -2,6 +2,7 @@ June 2025 9.2
  - TAK support added
  - Active Directory: allow to restore deleted entries in tree view (415)
  - Multi-edit tool: change operations are combined by DN to allow e.g. adding object classes with required attributes (408)
+ - Tree view: better editing of olcAccess (420)
  - Fixed bugs:
   -> Unix: profile editor for users not working (418)
   -> Custom fields: problems with deleting facsimileTelephoneNumber (419)
diff --git a/lam/lib/treeview.inc b/lam/lib/treeview.inc
index e63b48a37..062bfac49 100644
--- a/lam/lib/treeview.inc
+++ b/lam/lib/treeview.inc
@@ -754,7 +754,8 @@ class TreeView {
 		if (($schemaAttribute !== null) && $schemaAttribute->isBinary()) {
 			$value = base64_encode($value);
 		}
-		if ($isMultiLine) {
+		$value = $this->preProcessValue(strtolower($attributeName), $value);
+		if ($isMultiLine || $this->isPseudoMultiLine(strtolower($attributeName))) {
 			$inputField = new htmlInputTextarea('lam_attr_' . $attributeName, $value, 50, 5);
 		}
 		else {
@@ -1056,6 +1057,12 @@ class TreeView {
 				}
 			}
 		}
+		// olcAccess needs removal of newlines
+		if (isset($ldapChanges['olcaccess'])) {
+			for ($i = 0; $i < count($ldapChanges['olcaccess']); $i++) {
+				$ldapChanges['olcaccess'][$i] = str_replace("\n", ' ', $ldapChanges['olcaccess'][$i]);
+			}
+		}
 		// add ";binary" to binary attributes
 		foreach ($ldapChanges as $attributeName => $value) {
 			if (!isset($schemaAttributes[$attributeName])) {
@@ -1709,6 +1716,30 @@ class TreeView {
 		return json_encode([]);
 	}
 
+	/**
+	 * Returns if the attribute should be rendered multi-line even if it is single-line defined in schema.
+	 *
+	 * @param string $attributeName attribute name
+	 * @return bool render multi-line
+	 */
+	private function isPseudoMultiLine(string $attributeName): bool {
+		return ($attributeName === 'olcaccess');
+	}
+
+	/**
+	 * Preprocesses the value before rendering.
+	 *
+	 * @param string $attributeName attribute name
+	 * @param string $value value
+	 * @return string preprocessed value
+	 */
+	private function preProcessValue(string $attributeName, string $value): string {
+		if ($attributeName === 'olcaccess') {
+			return preg_replace('/\s+by\s+/', "\r\nby ", $value);
+		}
+		return $value;
+	}
+
 }
 
 /**
diff --git a/lam/templates/lib/500_lam.js b/lam/templates/lib/500_lam.js
index 5a58d3ca6..b780f9ad4 100644
--- a/lam/templates/lib/500_lam.js
+++ b/lam/templates/lib/500_lam.js
@@ -3182,7 +3182,10 @@ window.lam.treeview.updateAttributePositionData = function(containerId) {
 	const container = document.getElementById(containerId);
 	const childLiElements = container.children;
 	for (let i = 0; i < childLiElements.length; i++) {
-		const inputField = childLiElements[i].querySelector('input');
+		let inputField = childLiElements[i].querySelector('input');
+		if (inputField === null) {
+			inputField = childLiElements[i].querySelector('textarea');
+		}
 		inputField.value = '{' + i + '}' + inputField.value.replace(/^\{[0-9]+\}/, '');
 	}
 }