diff --git a/apps/user_ldap/lib/Helper.php b/apps/user_ldap/lib/Helper.php
index 74c7aa7a68..fb5b547810 100644
--- a/apps/user_ldap/lib/Helper.php
+++ b/apps/user_ldap/lib/Helper.php
@@ -165,7 +165,7 @@ class Helper {
 		');
 		$delRows = $query->execute(array($prefix.'%'));
 
-		if(\OCP\DB::isError($delRows)) {
+		if($delRows === null) {
 			return false;
 		}
 
diff --git a/lib/private/Tags.php b/lib/private/Tags.php
index 1b3505da5b..cc7bbf01ab 100644
--- a/lib/private/Tags.php
+++ b/lib/private/Tags.php
@@ -236,7 +236,7 @@ class Tags implements \OCP\ITags {
 					}
 					$entries[$objId][] = $row['category'];
 				}
-				if (\OCP\DB::isError($result)) {
+				if ($result === null) {
 					\OCP\Util::writeLog('core', __METHOD__. 'DB error: ' . \OCP\DB::getErrorMessage(), \OCP\Util::ERROR);
 					return false;
 				}
@@ -290,7 +290,7 @@ class Tags implements \OCP\ITags {
 		try {
 			$stmt = \OCP\DB::prepare($sql);
 			$result = $stmt->execute(array($tagId));
-			if (\OCP\DB::isError($result)) {
+			if ($result === null) {
 				\OCP\Util::writeLog('core', __METHOD__. 'DB error: ' . \OCP\DB::getErrorMessage(), \OCP\Util::ERROR);
 				return false;
 			}
@@ -532,7 +532,7 @@ class Tags implements \OCP\ITags {
 			$stmt = \OCP\DB::prepare('SELECT `id` FROM `' . self::TAG_TABLE . '` '
 				. 'WHERE `uid` = ?');
 			$result = $stmt->execute(array($arguments['uid']));
-			if (\OCP\DB::isError($result)) {
+			if ($result === null) {
 				\OCP\Util::writeLog('core', __METHOD__. 'DB error: ' . \OCP\DB::getErrorMessage(), \OCP\Util::ERROR);
 			}
 		} catch(\Exception $e) {
@@ -570,7 +570,7 @@ class Tags implements \OCP\ITags {
 			$stmt = \OCP\DB::prepare('DELETE FROM `' . self::TAG_TABLE . '` '
 				. 'WHERE `uid` = ?');
 			$result = $stmt->execute(array($arguments['uid']));
-			if (\OCP\DB::isError($result)) {
+			if ($result === null) {
 				\OCP\Util::writeLog('core', __METHOD__. ', DB error: ' . \OCP\DB::getErrorMessage(), \OCP\Util::ERROR);
 			}
 		} catch(\Exception $e) {
@@ -601,7 +601,7 @@ class Tags implements \OCP\ITags {
 			$updates[] = $this->type;
 			$stmt = \OCP\DB::prepare($query);
 			$result = $stmt->execute($updates);
-			if (\OCP\DB::isError($result)) {
+			if ($result === null) {
 				\OCP\Util::writeLog('core', __METHOD__. 'DB error: ' . \OCP\DB::getErrorMessage(), \OCP\Util::ERROR);
 				return false;
 			}
@@ -770,7 +770,7 @@ class Tags implements \OCP\ITags {
 							. 'WHERE `categoryid` = ?';
 					$stmt = \OCP\DB::prepare($sql);
 					$result = $stmt->execute(array($id));
-					if (\OCP\DB::isError($result)) {
+					if ($result === null) {
 						\OCP\Util::writeLog('core',
 							__METHOD__. 'DB error: ' . \OCP\DB::getErrorMessage(),
 							\OCP\Util::ERROR);
diff --git a/lib/public/DB.php b/lib/public/DB.php
index e132c5ff2e..f62f718029 100644
--- a/lib/public/DB.php
+++ b/lib/public/DB.php
@@ -78,22 +78,6 @@ class DB {
 		return \OC::$server->getDatabaseConnection()->insertIfNotExist($table, $input, $compare);
 	}
 
-	/**
-	 * Gets last value of autoincrement
-	 * @param string $table The optional table name (will replace *PREFIX*) and add sequence suffix
-	 * @return string
-	 *
-	 * \Doctrine\DBAL\Connection lastInsertID()
-	 *
-	 * Call this method right after the insert command or other functions may
-	 * cause trouble!
-	 * @deprecated 8.1.0 use lastInsertId() of \OCP\IDBConnection - \OC::$server->getDatabaseConnection()
-	 * @since 4.5.0
-	 */
-	public static function insertid($table=null) {
-		return (string)\OC::$server->getDatabaseConnection()->lastInsertId($table);
-	}
-
 	/**
 	 * Start a transaction
 	 * @deprecated 8.1.0 use beginTransaction() of \OCP\IDBConnection - \OC::$server->getDatabaseConnection()
@@ -112,27 +96,6 @@ class DB {
 		\OC::$server->getDatabaseConnection()->commit();
 	}
 
-	/**
-	 * Rollback the database changes done during a transaction that is in progress
-	 * @deprecated 8.1.0 use rollback() of \OCP\IDBConnection - \OC::$server->getDatabaseConnection()
-	 * @since 8.0.0
-	 */
-	public static function rollback() {
-		\OC::$server->getDatabaseConnection()->rollBack();
-	}
-
-	/**
-	 * Check if a result is an error, works with Doctrine
-	 * @param mixed $result
-	 * @return bool
-	 * @deprecated 8.1.0 Doctrine returns false on error (and throws an exception)
-	 * @since 4.5.0
-	 */
-	public static function isError($result) {
-		// Doctrine returns false on error (and throws an exception)
-		return $result === false;
-	}
-
 	/**
 	 * returns the error code and message as a string for logging
 	 * works with DoctrineException