diff --git a/wp-includes/sqlite/class-wp-sqlite-token.php b/wp-includes/sqlite/class-wp-sqlite-token.php
index 9976cf34..fbafd9e9 100644
--- a/wp-includes/sqlite/class-wp-sqlite-token.php
+++ b/wp-includes/sqlite/class-wp-sqlite-token.php
@@ -218,7 +218,7 @@ public function matches( $type = null, $flags = null, $values = null ) {
 		return (
 			( null === $type || $this->type === $type )
 			&& ( null === $flags || ( $this->flags & $flags ) )
-			&& ( null === $values || in_array( strtoupper( $this->value ), $values, true ) )
+			&& ( null === $values || in_array( strtoupper( $this->value ?? '' ), $values, true ) )
 		);
 	}
 
@@ -241,7 +241,7 @@ public function is_semantically_void() {
 	private function extract() {
 		switch ( $this->type ) {
 			case self::TYPE_KEYWORD:
-				$this->keyword = strtoupper( $this->token );
+				$this->keyword = strtoupper( $this->token ?? '' );
 				if ( ! ( $this->flags & self::FLAG_KEYWORD_RESERVED ) ) {
 					/*
 					 * Unreserved keywords should stay the way they are
@@ -256,7 +256,7 @@ private function extract() {
 				return ' ';
 
 			case self::TYPE_BOOL:
-				return strtoupper( $this->token ) === 'TRUE';
+				return strtoupper( $this->token ?? '' ) === 'TRUE';
 
 			case self::TYPE_NUMBER:
 				$ret = str_replace( '--', '', $this->token ); // e.g. ---42 === -42.
diff --git a/wp-includes/sqlite/class-wp-sqlite-translator.php b/wp-includes/sqlite/class-wp-sqlite-translator.php
index 284afe0e..d0bf0926 100644
--- a/wp-includes/sqlite/class-wp-sqlite-translator.php
+++ b/wp-includes/sqlite/class-wp-sqlite-translator.php
@@ -1550,7 +1550,7 @@ private function skip_index_hint() {
 				array( 'JOIN', 'ORDER', 'GROUP' )
 			) ) {
 				$this->rewriter->skip(); // JOIN, ORDER, GROUP.
-				if ( 'BY' === strtoupper( $this->rewriter->peek()->value ) ) {
+				if ( 'BY' === strtoupper( $this->rewriter->peek()->value ?? '' ) ) {
 					$this->rewriter->skip(); // BY.
 				}
 			}
@@ -1572,7 +1572,7 @@ private function skip_index_hint() {
 	 */
 	private function execute_truncate() {
 		$this->rewriter->skip(); // TRUNCATE.
-		if ( 'TABLE' === strtoupper( $this->rewriter->peek()->value ) ) {
+		if ( 'TABLE' === strtoupper( $this->rewriter->peek()->value ?? '' ) ) {
 			$this->rewriter->skip(); // TABLE.
 		}
 		$this->rewriter->add( new WP_SQLite_Token( 'DELETE', WP_SQLite_Token::TYPE_KEYWORD ) );
@@ -2036,7 +2036,7 @@ private function skip_from_dual( $token ) {
 			return false;
 		}
 		$from_table = $this->rewriter->peek_nth( 2 )->value;
-		if ( 'DUAL' !== strtoupper( $from_table ) ) {
+		if ( 'DUAL' !== strtoupper( $from_table ?? '' ) ) {
 			return false;
 		}
 
@@ -2558,7 +2558,7 @@ private function capture_group_by( $token ) {
 			return false;
 		}
 		$next = $this->rewriter->peek_nth( 2 )->value;
-		if ( 'BY' !== strtoupper( $next ) ) {
+		if ( 'BY' !== strtoupper( $next ?? '' ) ) {
 			return false;
 		}
 
@@ -2909,8 +2909,8 @@ private function execute_alter() {
 					new WP_SQLite_Token( $this->table_name, WP_SQLite_Token::TYPE_KEYWORD ),
 				)
 			);
-			$op_type          = strtoupper( $this->rewriter->consume()->token );
-			$op_subject       = strtoupper( $this->rewriter->consume()->token );
+			$op_type          = strtoupper( $this->rewriter->consume()->token ?? '' );
+			$op_subject       = strtoupper( $this->rewriter->consume()->token ?? '' );
 			$mysql_index_type = $this->normalize_mysql_index_type( $op_subject );
 			$is_index_op      = (bool) $mysql_index_type;
 
@@ -3245,8 +3245,8 @@ private function execute_drop() {
 	 */
 	private function execute_show() {
 		$this->rewriter->skip();
-		$what1 = strtoupper( $this->rewriter->consume()->token );
-		$what2 = strtoupper( $this->rewriter->consume()->token );
+		$what1 = strtoupper( $this->rewriter->consume()->token ?? '' );
+		$what2 = strtoupper( $this->rewriter->consume()->token ?? '' );
 		$what  = $what1 . ' ' . $what2;
 		switch ( $what ) {
 			case 'CREATE PROCEDURE':