diff --git a/apps/user_ldap/lib/Mapping/AbstractMapping.php b/apps/user_ldap/lib/Mapping/AbstractMapping.php
index 16973f76ff4d8..1a747cc8bfd4d 100644
--- a/apps/user_ldap/lib/Mapping/AbstractMapping.php
+++ b/apps/user_ldap/lib/Mapping/AbstractMapping.php
@@ -438,14 +438,14 @@ public function clearCb(callable $preCallback, callable $postCallback): bool {
 		$picker = $this->dbc->getQueryBuilder();
 		$picker->select('owncloud_name')
 			->from($this->getTableName());
-		$cursor = $picker->execute();
+		$cursor = $picker->executeQuery();
 		$result = true;
-		while ($id = $cursor->fetchOne()) {
+		while (($id = $cursor->fetchOne()) !== false) {
 			$preCallback($id);
 			if ($isUnmapped = $this->unmap($id)) {
 				$postCallback($id);
 			}
-			$result &= $isUnmapped;
+			$result = $result && $isUnmapped;
 		}
 		$cursor->closeCursor();
 		return $result;
diff --git a/apps/user_ldap/lib/Migration/Version1130Date20211102154716.php b/apps/user_ldap/lib/Migration/Version1130Date20211102154716.php
index 2cca72ac4934d..3f590df7fa5e3 100644
--- a/apps/user_ldap/lib/Migration/Version1130Date20211102154716.php
+++ b/apps/user_ldap/lib/Migration/Version1130Date20211102154716.php
@@ -259,7 +259,7 @@ protected function getNextcloudIdsByUuid(string $table, string $uuid): array {
 
 		$result = $select->executeQuery();
 		$idList = [];
-		while ($id = $result->fetchOne()) {
+		while (($id = $result->fetchOne()) !== false) {
 			$idList[] = $id;
 		}
 		$result->closeCursor();
@@ -278,7 +278,7 @@ protected function getDuplicatedUuids(string $table): Generator {
 			->having($select->expr()->gt($select->func()->count('owncloud_name'), $select->createNamedParameter(1)));
 
 		$result = $select->executeQuery();
-		while ($uuid = $result->fetchOne()) {
+		while (($uuid = $result->fetchOne()) !== false) {
 			yield $uuid;
 		}
 		$result->closeCursor();
diff --git a/apps/workflowengine/lib/Manager.php b/apps/workflowengine/lib/Manager.php
index 178bc87365b76..34dbf507b9191 100644
--- a/apps/workflowengine/lib/Manager.php
+++ b/apps/workflowengine/lib/Manager.php
@@ -351,7 +351,7 @@ protected function canModify(int $id, ScopeContext $scopeContext):bool {
 		$result = $qb->execute();
 
 		$this->operationsByScope[$scopeContext->getHash()] = [];
-		while ($opId = $result->fetchOne()) {
+		while (($opId = $result->fetchOne()) !== false) {
 			$this->operationsByScope[$scopeContext->getHash()][] = (int)$opId;
 		}
 		$result->closeCursor();
diff --git a/apps/workflowengine/lib/Migration/PopulateNewlyIntroducedDatabaseFields.php b/apps/workflowengine/lib/Migration/PopulateNewlyIntroducedDatabaseFields.php
index 019d3ae6bcc24..974793e99b24e 100644
--- a/apps/workflowengine/lib/Migration/PopulateNewlyIntroducedDatabaseFields.php
+++ b/apps/workflowengine/lib/Migration/PopulateNewlyIntroducedDatabaseFields.php
@@ -57,7 +57,7 @@ protected function populateScopeTable(IResult $ids): void {
 		$qb = $this->dbc->getQueryBuilder();
 
 		$insertQuery = $qb->insert('flow_operations_scope');
-		while ($id = $ids->fetchOne()) {
+		while (($id = $ids->fetchOne()) !== false) {
 			$insertQuery->values(['operation_id' => $qb->createNamedParameter($id), 'type' => IManager::SCOPE_ADMIN]);
 			$insertQuery->execute();
 		}