PHP 7.4 has reached end of life. I am trying to update to PHP 8.2 however there are a number of compatibility issues which must be addressed by Authorize.net. The PHP SDK has not been updated in over 3 years, meaning that the SDK is not compatible with any currently-supported version of PHP.
I have the same issues as other contributors on this thread:
Issues have been reported here as well, without a meaningful response:
Please advise if the PHP SDK continues to be supported and when updates to resolve these problems are expected, or if it is no longer being supported.
PHP 7.4 is not secure and Authorize.net's lack of simple compatibility updates puts customers at risk. If there is no further support, the entire SDK should be withdrawn. Lack of solutions and clarity regarding this matter undermine all other efforts by Authorize.net to secure client installations.
As I mentioned in https://community.developer.cybersource.com/t5/Integration-and-Testing/Upgrading-PHP-SDK-to-PHP-8-1/...
I spoke to someone at Authorize.net today and they are aware of the issue. They have been contacted by several merchants encountering the same error. Keep the pressure on the support team and open tickets at https://support.authorize.net/. They said they will update the SDK soon. Make sure to point out that PHP 8.1 is the current (stable version of PHP). 8.0 is no longer supported: https://www.php.net/supported-versions.php.