I have to upgrade a production php webserver from php-5.6 to 7.2. While upgrading to 7.2 I run to lot of deprecation inside 3d-party libraries. I did not developed the project. And it seems that the project does not use any package manager software (like composer).
The first deprecation error is located in nette.php (Nette) but I am afraid that there will be more deprecation errors.
What would be the best approach to tackle this task?
A good approach would be to use composer to install the 3rd party libraries as they are right now, using the current versions. This gives you the ability to go back to the old situation very easily. Then you upgrade the libraries one by one, checking for compatibility and changing the project specific code related to that library.