I'm in the process of upgrading Magento and encountering the following error. I'm unsure how to resolve it. Here's the error message.

Deprecated: Return type of phpseclib_mcrypt_filter::filter($in, $out, &$consumed, $closing) should either be compatible with php_user_filter::filter($in, $out, &$consumed, bool $closing): int, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in /home/mindtree/public_html/dev/vendor/phpseclib/mcrypt_compat/lib/mcrypt.php on line 1107

1 Answer 1


mcrypt module is depricated from php 8.1

Check if mcrypt module is there

Run command from terminal : php -m

If mcrypt module is listed, disable it in php8.1

Restart php

  • I already checked it mcrypt is not there.
    – user92141
    Oct 4, 2023 at 4:52
  • Verify once from phpinfo.php
    – MP Raj
    Oct 4, 2023 at 5:00
  • I used the command php -m to list the modules, but I couldn't find mcrypt in the list.
    – user92141
    Oct 4, 2023 at 5:35

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