Error Reproduced

This eror happen amongst many of the SaaS GovCMS websites, where after the after installing the site locally, imported the production database, and login as administrator using pygmy & ahoy, the first thing you see is:

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DEPRECATED FUNCTION: STR_REPLACE: PASSING NULL TO PARAMETER #3 ($SUBJECT) OF TYPE ARRAY | STRING IS DEPRECATED IN CONFIG_PERMS_PARSE_ PATHO (LINE 41 OF MODULES/CONTRIB/CONFIG_PERMS/CONFIG_PERMS.MODULE).
(* the same message got printed for multiple times

Also refer to the following screenshot:

2025-02-03T151630

Cause of the Error

The error message you encountered, DEPRECATED FUNCTION: STR_REPLACE: PASSING NULL TO PARAMETER #3 ($SUBJECT) OF TYPE ARRAY | STRING IS DEPRECATED, is related to a change in PHP 8.1. This change deprecates passing null to certain parameters of built-in functions, including the third parameter ($subject) of the str_replace() function. Here’s a breakdown of the issue:

  1. PHP 8.1 Deprecation: In PHP 8.1, passing null to parameters that expect a non-nullable type (like array|string) is deprecated. Previously, such cases were silently converted to an empty string or handled without error.
  2. Code Issue: The error occurs because the $subject parameter being passed to str_replace() is null. This often happens due to:
    • A variable not being initialized properly.
    • A function (like preg_replace()) returning null due to an error or invalid input, which is then passed to str_replace().

Resolving the Error

To fix this issue, you need to ensure that the $subject parameter passed to str_replace() is never null. For my instance, I simply need to add a null check before calling str_replace(), and provide a default value (like an empty string) in case it is nul.

For example:

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/* ----------- BEFORE (LINE: 41) */
function config_perms_parse_path($route) {
  if (is_array($route)) {
    $string = implode("\n", $route);
    return $string;
  }
  else {
    $route = str_replace(["\r\n", "\n\r", "\n", "\r"], "\n", $route);
    $parts = explode("\n", $route);

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/* ----------- AFTER (LINE: 41) */
function config_perms_parse_path($route) {
  if (is_array($route)) {
    $string = implode("\n", $route);
    return $string;
  }
  else {
    $route = $route  ?? ''; /* <----- ADDING THIS !!!!!!!!!!!*/
    $route = str_replace(["\r\n", "\n\r", "\n", "\r"], "\n", $route);
    $parts = explode("\n", $route);

In your specific case, the error maybe coming from somewhere else, and you’ll need to read the error message carefully (and debug upstream function potentially) to find out exactly where it comes from.

Alternatively, you can also quickly surpress the error by uninstalling the module that holds this erronous code, for the above example, the error message is:

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DEPRECATED FUNCTION: STR_REPLACE: PASSING NULL TO PARAMETER #3 ($SUBJECT) OF TYPE ARRAY | STRING IS DEPRECATED IN CONFIG_PERMS_PARSE_ PATHO (LINE 41 OF MODULES/CONTRIB/CONFIG_PERMS/CONFIG_PERMS.MODULE).
(* the same message got printed for multiple times

Hence we can derive it comes from the module Custom Permissions (config_perms), and as a result you can surpress the issue by simply uninstalling this module; But if you do this, please keep in mind this change though-out your local development, and make sure you don’t push this as a part of the configuration (config sync) to the git repository.