PHP Deprecated: ltrim() in formatting esc_url.

[neo2k23]

I am getting constant these warnings in my error log file.

[22-May-2024 13:00:43 UTC] PHP Deprecated: ltrim(): Passing null to parameter #1 ($string) of type string is deprecated in /.../wp-includes/formatting.php on line 4482

it is caused by this code

<?php
        $original_url = $url;

        if ( '' === $url ) {
                return $url;
        }

        $url = str_replace( ' ', '%20', ltrim( $url ) );

The last line is line 4482

If i change line 4478 to this it does not happen anymore.

<?php
        $original_url = $url;

        if ( '' === $url  || empty ($url)) {
                return $url;
        }

        $url = str_replace( ' ', '%20', ltrim( $url ) );

Since any information is missing on the location which is calling esc_url it is hard to debug which theme code or plugin code is responsible for this.

Can someone please explain to me what is going on here?

Thank you

[siliconforks]

Replying to neo2k23:

Since any information is missing on the location which is calling esc_url it is hard to debug which theme code or plugin code is responsible for this.

You could try adding some code like this:

if ( empty( $url ) ) {
        error_log( print_r( debug_backtrace( DEBUG_BACKTRACE_IGNORE_ARGS ), true ) );
}

That should record in the error log whoever is calling esc_url() with an empty argument.

[neo2k23]

Thank you for the reply... i get these

[22-May-2024 15:09:38 UTC] Array
(
    [0] => Array
        (
            [file] => /home/public_html/wp-content/plugins/maintenance/load/index.php
            [line] => 68
            [function] => esc_url
        )

    [1] => Array
        (
            [file] => /home/public_html/wp-includes/template-loader.php
            [line] => 106
            [args] => Array
                (
                    [0] => /home/public_html/wp-content/plugins/maintenance/load/index.php
                )

            [function] => include
        )

    [2] => Array
        (
            [file] => /home/public_html/wp-blog-header.php
            [line] => 19
            [args] => Array
                (
                    [0] => /home/public_html/wp-includes/template-loader.php
                )

            [function] => require_once
        )

    [3] => Array
        (
            [file] => /home/public_html/index.php
            [line] => 17
            [args] => Array
                (
                    [0] => /home/public_html/wp-blog-header.php
                )

            [function] => require
        )

)

[22-May-2024 15:09:38 UTC] PHP Deprecated:  ltrim(): Passing null to parameter #1 ($string) of type string is deprecated in /home/public_html/wp-includes/formatting.php on line 4486
[22-May-2024 15:09:41 UTC] Array
(
    [0] => Array
        (
            [file] => /home/public_html/wp-content/plugins/maintenance/load/index.php
            [line] => 68
            [function] => esc_url
        )

    [1] => Array
        (
            [file] => /home/public_html/wp-includes/template-loader.php
            [line] => 106
            [args] => Array
                (
                    [0] => /home/public_html/wp-content/plugins/maintenance/load/index.php
                )

            [function] => include
        )

    [2] => Array
        (
            [file] => /home/public_html/wp-blog-header.php
            [line] => 19
            [args] => Array
                (
                    [0] => /home/public_html/wp-includes/template-loader.php
                )

            [function] => require_once
        )

    [3] => Array
        (
            [file] => /home/public_html/index.php
            [line] => 17
            [args] => Array
                (
                    [0] => /home/public_html/wp-blog-header.php
                )

            [function] => require
        )

)

[22-May-2024 15:09:41 UTC] PHP Deprecated:  ltrim(): Passing null to parameter #1 ($string) of type string is deprecated in /home/public_html/wp-includes/formatting.php on line 4486

But should formatting not deal with this so the issue does not occur at all? because now everybody calling esc_url has to check if the url does not contain null or is empty.

Please advice!

thank you

[siliconforks]

Replying to neo2k23:

But should formatting not deal with this so the issue does not occur at all? because now everybody calling esc_url has to check if the url does not contain null or is empty.

Maybe, but I think it is generally considered best policy for bugs like this to fix the caller, as the caller should not be passing empty values to esc_url. See, for example, ticket #59154, which is a similar issue to yours (where the fix was to fix the caller rather than change esc_url).

However, your issue looks a bit more complicated as it seems that the caller is the ​Maintenance plugin but it looks like the caller is not really at fault here. I would guess you have some other plugin installed which disables XML-RPC?

It might be helpful to post a list of all active plugins on your site. (You can get this in the admin section by going to Tools → Site Health → Info → Active Plugins.)

[sabernhardt]

This specific issue needs to be reported on the ​Maintenance plugin support forum (and others).

​The pingback URL uses esc_url() around bloginfo(), the echo function, instead of using get_bloginfo() like this (from Twenty Ten):
<?php echo esc_url( get_bloginfo( 'pingback_url' ) ); ?>

Additional ​plugins and ​themes have esc_url() with bloginfo(), too.

At least two security plugins replace 'pingback_url' with an empty string, which should avoid the deprecation warnings, but that can still result in an empty link href.

The if ( '' == $url ) condition goes back to [1132], when the function was named clean_url(), and the comparison became strict in [47808].

[neo2k23]

Replying to siliconforks:

Replying to neo2k23:

However, your issue looks a bit more complicated as it seems that the caller is the ​Maintenance plugin but it looks like the caller is not really at fault here. I would guess you have some other plugin installed which disables XML-RPC?

It might be helpful to post a list of all active plugins on your site. (You can get this in the admin section by going to Tools → Site Health → Info → Active Plugins.)

There is no such plugin active but the hoster blocks calls to XML-RPC.php

I will report it to the maintanenance mode plugin developer.

I still believe that checking in the esc_url function for being null would not lead to all the plugins and theme developers to add their checks before calling esc_url. Which would be preferable.

Until php 8.1 there was no warning and the return would still be a empty url. What is against checking in the esc_url function?

Thank you for the replies and support.

[siliconforks]

Replying to neo2k23:

Until php 8.1 there was no warning and the return would still be a empty url. What is against checking in the esc_url function?

The problem is that when a caller calls esc_url() with an empty argument, it's almost always a bug in the caller, so it's better to fix it in the caller's code. In the case of the Maintenance plugin - their code is subtly wrong (I didn't notice this at first - thanks to @sabernhardt for pointing this out) - it's calling bloginfo() instead of get_bloginfo(). So that's an issue which needs to be fixed in their code. Modifying esc_url() to eliminate the warning would really just be masking the issue - it wouldn't actually be fixing the source of the problem.

[robinmartijn]

Replying to siliconforks:

Modifying esc_url() to eliminate the warning would really just be masking the issue - it wouldn't actually be fixing the source of the problem.

It’s not just a warning, it’s a deprecation. If we don’t fix this, it will result in actual errors in a future PHP version.

[sabernhardt]

#61544 was marked as a duplicate.