Fatal error in wp_insert_term() when the term name is not a string by josephscott · Pull Request #13521 · WordPress/wordpress-develop

josephscott · 2026-09-14T20:04:46Z

https://core.trac.wordpress.org/ticket/66108

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This Pull Request is for code review only. Please keep all other discussion in the Trac ticket. Do not merge this Pull Request. See GitHub Pull Requests for Code Review in the Core Handbook for more details.

https://core.trac.wordpress.org/ticket/66108

github-actions · 2026-09-14T20:04:57Z

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github-actions · 2026-09-14T20:07:45Z

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robelsust · 2026-09-25T13:39:44Z

Tested and Verified ✅

Environment:

WordPress: 7.2-alpha (trunk)
PHP: 8.3

Verification:

Before Patch (trunk):
- wp_insert_term( array( 'foo' ), 'post_tag' ) throws a fatal TypeError: trim(): Argument #1 ($string) must be of type string, array given.
- XML-RPC wp.newPost with array in terms_names triggers HTTP 500 instead of a structured XML-RPC fault.
After PR Fatal error in wp_insert_term() when the term name is not a string #13521:
- wp_insert_term() safely returns WP_Error( 'empty_term_name' ) for non-scalar $term values without fatals.
- Numeric term names (2024, 1.5) continue to work properly as strings.
- XML-RPC _insert_post() cleanly returns IXR_Error( 403, 'Invalid term name.' ).
- PHPUnit:
  - tests/phpunit/tests/term/wpInsertTerm.php: Pass (43 tests, 166 assertions)
  - tests/phpunit/tests/xmlrpc/wp/newPost.php: Pass (32 tests, 78 assertions)
  - Full --group taxonomy: Pass (913 tests, 2383 assertions)
  - Full --group xmlrpc: Pass (356 tests, 1339 assertions)
- PHPCS: 0 errors, 0 warnings on changed lines.

Regarding the discussion on JSON Schema adoption for XML-RPC: while a future schema-driven sanitization layer for XML-RPC is a worthy initiative, this PR addresses a real PHP 8+ fatal error in wp_insert_term() and _insert_post() cleanly and without breaking changes. Recommending approval.

westonruter · 2026-09-25T15:50:58Z


 					$term_names = $post_data['terms_names'][ $taxonomy ];
 					foreach ( $term_names as $term_name ) {
+						if ( ! is_string( $term_name ) ) {


Good. This addresses an existing PHPStan error on code below:

westonruter · 2026-09-25T15:57:39Z

-	if ( '' === trim( $term ) ) {
+	if ( ! is_scalar( $term ) || '' === trim( $term ) ) {


Is this just a hardening? Is it needed for the above fix. PHPStan isn't complaining here because $term comes from the return value of the pre_insert_term filter which is typed as string|WP_Error. It is first checked to see if it is a WP_Error in which it returns, so then the type narrows to string.

I think this is a case where the callers should be fixing the types that they pass into the wp_insert_term() function.

For the XML-RPC case it is not strictly needed.

It is first checked to see if it is a WP_Error in which it returns, so then the type narrows to string.

I don't think that is accurate, which is why we have an is_int() call as well - https://github.com/WordPress/wordpress-develop/blame/trunk/src/wp-includes/taxonomy.php#L2595

Anything that calls wp_insert_term() directly can cause a problem. Here is an example without this fix:

$ npm run env:cli --silent -- eval 'var_dump( wp_insert_term( array( "foo" ), "post_tag" ) );' Fatal error: Uncaught TypeError: trim(): Argument #1 ($string) must be of type string, array given in /var/www/src/wp-includes/taxonomy.php:2599 Stack trace: #0 /var/www/src/wp-includes/taxonomy.php(2599): trim(Array) #1 phar:///usr/local/bin/wp/vendor/wp-cli/eval-command/src/Eval_Command.php(39) : eval()'d code(1): wp_insert_term(Array, 'post_tag') #2 phar:///usr/local/bin/wp/vendor/wp-cli/eval-command/src/Eval_Command.php(39): eval() #3 [internal function]: Eval_Command->__invoke(Array, Array) #4 phar:///usr/local/bin/wp/vendor/wp-cli/wp-cli/php/WP_CLI/Dispatcher/CommandFactory.php(100): call_user_func(Array, Array, Array) #5 [internal function]: WP_CLI\Dispatcher\CommandFactory::WP_CLI\Dispatcher\{closure}(Array, Array) #6 phar:///usr/local/bin/wp/vendor/wp-cli/wp-cli/php/WP_CLI/Dispatcher/Subcommand.php(497): call_user_func(Object(Closure), Array, Array) #7 phar:///usr/local/bin/wp/vendor/wp-cli/wp-cli/php/WP_CLI/Runner.php(470): WP_CLI\Dispatcher\Subcommand->invoke(Array, Array, Array) #8 phar:///usr/local/bin/wp/vendor/wp-cli/wp-cli/php/WP_CLI/Runner.php(493): WP_CLI\Runner->run_command(Array, Array) #9 phar:///usr/local/bin/wp/vendor/wp-cli/wp-cli/php/WP_CLI/Runner.php(136): WP_CLI\Runner->run_command_and_exit() #10 phar:///usr/local/bin/wp/vendor/wp-cli/wp-cli/php/WP_CLI/Runner.php(1228): WP_CLI\Runner->do_early_invoke('before_wp_load') #11 phar:///usr/local/bin/wp/vendor/wp-cli/wp-cli/php/WP_CLI/Bootstrap/LaunchRunner.php(28): WP_CLI\Runner->start() #12 phar:///usr/local/bin/wp/vendor/wp-cli/wp-cli/php/bootstrap.php(84): WP_CLI\Bootstrap\LaunchRunner->process(Object(WP_CLI\Bootstrap\BootstrapState)) #13 phar:///usr/local/bin/wp/vendor/wp-cli/wp-cli/php/wp-cli.php(35): WP_CLI\bootstrap() #14 phar:///usr/local/bin/wp/php/boot-phar.php(20): include('phar:///usr/loc...') #15 /usr/local/bin/wp(4): include('phar:///usr/loc...') #16 {main} thrown in /var/www/src/wp-includes/taxonomy.php on line 2599 Error: There has been a critical error on this website.Learn more about troubleshooting WordPress. There has been a critical error on this website.

And here is the same call with this fix:

$ npm run env:cli --silent -- eval 'var_dump( wp_insert_term( array( "foo" ), "post_tag" ) );' object(WP_Error)#2540 (3) { ["errors"]=> array(1) { ["empty_term_name"]=> array(1) { [0]=> string(33) "A name is required for this term." } } ["error_data"]=> array(0) { } ["additional_data":protected]=> array(0) { } }

westonruter · 2026-09-25T15:59:39Z

+	 * @param mixed $term The term name to insert.
+	 */
+	public function test_wp_insert_term_non_scalar_term_name( $term ): void {
+		$found = wp_insert_term( $term, 'post_tag' );


Per above, PHPStan is already flagging this as an error:

westonruter · 2026-09-25T16:01:35Z

+	 * @param int|float $term The term name to insert.
+	 */
+	public function test_wp_insert_term_numeric_term_name( $term ): void {
+		$found = wp_insert_term( $term, 'post_tag' );


PHPStan is also flagging this:

If we keep it:

Suggested change

$found = wp_insert_term( $term, 'post_tag' );

$found = wp_insert_term( $term, 'post_tag' ); // @phpstan-ignore argument.type (Intentionally passing scalars.)

westonruter · 2026-09-25T16:03:28Z

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+	public function test_wp_insert_term_numeric_term_name( $term ): void {
+		$found = wp_insert_term( $term, 'post_tag' );
+
+		$this->assertNotWPError( $found );


Slightly better:

Suggested change

$this->assertNotWPError( $found );

$this->assertIsArray( $found );

Due to:

However, this will become irrelevant with #13614. So feel free to leave alone.

@robelsust This looks like an AI-generated review comment without disclosure on the tooling or model used. So I'm hiding the comment.

Apologies for that, @westonruter. I used AI assistance to help formulate the review notes after testing the PHP 8.3 runtime behavior locally, and I omitted the required AI disclosure block.

Use of AI Tools

AI assistance: Yes

Used for: Helping summarize review notes after local testing on PHP 8.3; reviewed and posted by me.

Completely understand hiding the comment to uphold core review standards. Thanks for keeping the standards high!

Fatal error in wp_insert_term() when the term name is not a string

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https://core.trac.wordpress.org/ticket/66108

westonruter requested changes Sep 25, 2026

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Fatal error in wp_insert_term() when the term name is not a string - #13521

Fatal error in wp_insert_term() when the term name is not a string#13521
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josephscott:66108/avoid-fatal-on-term-name

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		if ( '' === trim( $term ) ) {
		if ( ! is_scalar( $term ) \|\| '' === trim( $term ) ) {

	$found = wp_insert_term( $term, 'post_tag' );
	$found = wp_insert_term( $term, 'post_tag' ); // @phpstan-ignore argument.type (Intentionally passing scalars.)

	$this->assertNotWPError( $found );
	$this->assertIsArray( $found );

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Test using WordPress Playground

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robelsust commented Sep 25, 2026

Tested and Verified ✅

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github-actions Bot commented Sep 14, 2026 •

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