Notice: iconv(): Detected an illegal character in input string

This probably comes from another plugin or the site’s theme. Are you seeing it in the Wordfence scan results, or somewhere else that is related to Wordfence?

Wordfence scans turn on extra error reporting, so they can pick up errors from other plugins. This might not be harmful, but could at least mean that there is a badly formatted character somewhere on the site (such as a letter with an accent mark, or certain symbols.)

You might be able to find out if it’s coming from a plugin or theme by disabling plugins or temporarily switching themes, and if the warning goes away, you can enable them one at a time, and see which one causes it to come back.

-Matt R

Yep, it is coming from the iconv() function that is defined in formatting.php, but it could be that the function is called (directly or indirectly) from a plugin or theme. It could be part of the WordPress core calling the function too — it’s usually less likely to find a new bug in the core this long after the last release though.

If you can’t track down the source of the error by disabling plugins, I sometimes use the plugin “Query Monitor”, which puts a line on the admin bar, and can be used to show more information about errors. If this error is happening on normal pages too, even though it’s normally hidden, that should make it easy to track down.

I don’t recommend leaving Query Monitor enabled all the time on a production site though — I have had minor compatibility issues with other plugins, including one or two that make xml sitemaps. It can be very helpful for troubleshooting though.

-Matt R