Hi
Notice undefined index sounds like a PHP error rmessage to me. This is caused by poor code usually.
It is quite possible that the errors have become apparent in the new release of WAMPServer, because as a development tool it comes configured to diaply PHP error message that exist.
Quite possibly you had turned Off error reporting in your old system therefore allowing you to ignore all the bad code.
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(Windows 10 Pro 64bit) (Wampserver 3.3.4 64bit) Aestan Tray Menu 3.2.5.4
<Apache versions MULTIPE> <PHP versions MULTIPLE> <MySQL Versions MULTIPLE>
<MariaDB versions MULTIPLE> <phpMyAdmin versions MULTIPLE> <MySQL Workbench 8.0.23>Read The Manuals Apache --
MySQL --
PHP --
phpMyAdminGet your Apache/MySQL/mariaDB/PHP ADDONs here from the
WAMPServer alternate Repo-X-X-X-
Backup your databases regularly Here is How dont regret it later! Yes even when developing -X-X-X-