diff --git a/classes/announcement/AnnouncementDAO.inc.php b/classes/announcement/AnnouncementDAO.inc.php
index dfc9d189713..01d2e9d7e26 100644
--- a/classes/announcement/AnnouncementDAO.inc.php
+++ b/classes/announcement/AnnouncementDAO.inc.php
@@ -104,7 +104,7 @@ function getByAssocId($assocType, $assocId) {
 			->orderByDesc('date_posted')
 			->get();
 		foreach ($result as $row) {
-			yield $this->_fromRow((array) $row);
+			yield $row->announcement_id => $this->_fromRow((array) $row);
 		}
 	}
 
@@ -120,7 +120,7 @@ function getByTypeId($typeId) {
 			$rangeInfo
 		);
 		foreach ($result as $row) {
-			yield $this->_fromRow((array) $row);
+			yield $row->announcement_id => $this->_fromRow((array) $row);
 		}
 	}
 
diff --git a/classes/announcement/AnnouncementTypeDAO.inc.php b/classes/announcement/AnnouncementTypeDAO.inc.php
index df9443e4d20..4ebedfd053a 100644
--- a/classes/announcement/AnnouncementTypeDAO.inc.php
+++ b/classes/announcement/AnnouncementTypeDAO.inc.php
@@ -167,7 +167,7 @@ function getByAssoc($assocType, $assocId) {
 			[(int) $assocType, (int) $assocId]
 		);
 		foreach ($result as $row) {
-			yield $this->_fromRow((array) $row);
+			yield $row->type_id => $this->_fromRow((array) $row);
 		}
 	}
 
diff --git a/classes/components/forms/announcement/PKPAnnouncementForm.inc.php b/classes/components/forms/announcement/PKPAnnouncementForm.inc.php
index 66593c6f396..b5743429e89 100644
--- a/classes/components/forms/announcement/PKPAnnouncementForm.inc.php
+++ b/classes/components/forms/announcement/PKPAnnouncementForm.inc.php
@@ -64,7 +64,7 @@ public function __construct($action, $locales, $announcementContext) {
 		$announcementTypeDao = \DAORegistry::getDAO('AnnouncementTypeDAO');
 		$announcementTypes = $announcementTypeDao->getByAssoc(\Application::get()->getContextAssocType(), $announcementContext->getId());
 		$announcementOptions = [];
-		while ($announcementType = $announcementTypes->next()) {
+		foreach ($announcementTypes as $announcementType) {
 			$announcementOptions[] = [
 				'value' => (int) $announcementType->getId(),
 				'label' => $announcementType->getLocalizedTypeName(),
diff --git a/classes/migration/upgrade/PKPv3_3_0UpgradeMigration.inc.php b/classes/migration/upgrade/PKPv3_3_0UpgradeMigration.inc.php
index 6576ba58895..04c24ad4fcc 100755
--- a/classes/migration/upgrade/PKPv3_3_0UpgradeMigration.inc.php
+++ b/classes/migration/upgrade/PKPv3_3_0UpgradeMigration.inc.php
@@ -55,6 +55,10 @@ public function up() {
 			// pkp/pkp-lib#5865 Change announcement expiry format in database
 			$table->date('date_expire')->change();
 		});
+		Capsule::schema()->table('announcement_settings', function (Blueprint $table) {
+			// pkp/pkp-lib#6748 Change announcement setting type to permit nulls
+			$table->string('setting_type', 6)->nullable()->change();
+		});
 
 		// Transitional: The stage_id column may have already been added by the ADODB schema toolset
 		if (!Capsule::schema()->hasColumn('email_templates_default', 'stage_id')) {