`CakeResponse` referencing undefined variables in `compact()` call triggers errors/notices

Question

I'm updating my first CakePHP application on a web server, but pages show errors which are at the end of this post. I can't find the file(s) which have not uploded correctly. Thanks for help.

CakePHP version: 2.9

Error messages:

Notice (8): compact(): Undefined variable: etagMatches [CORE/Cake/Network/CakeResponse.php, line 1171]*

Notice (8): compact() [function.compact]: Undefined variable: timeMatches [CORE/Cake/Network/CakeResponse.php, line 1171]*

Notice (8): compact() [function.compact]: Undefined variable: subject [CORE/Cake/Utility/ObjectCollection.php, line 128]*

Answer 1

As of PHP 7.3 compact() will trigger an error when referencing undefined variables.

This has been fixed in CakePHP 2.10.13, either upgrade your application (preferred), or downgrade your PHP version.

https://github.com/cakephp/cakephp/pull/12487