How to properly update?

Question

1C-Bitrix

There is a site on Bitrix Business, virtual machine, php 5.6. Version 14. Worked in win-1251
Bought a new Bitrix Small Business license (version below). Version 18, latest i.e. It is logical that she will ask for php 7. We want utf-8.
What is the update algorithm?
After all, if you immediately slip the key, the site will fall and the update will most likely not get up correctly due to a php error.
If you first update PHP, then the site will not start and the key cannot be palmed off and updated.
When and at what point to change the site encoding, before or after the update?
It's still not entirely clear:
I have another domain, on which is a copy of the original site, on this copy I do testing and development.
It is logical that you can update the copy, and if everything goes well, upload the copy to the original site.
Question - how not to fly off the license with these updates on test copies?
(the Bitrix forum, as it died 10 years ago, is still silent, there are no answers even to simple questions)

Answer 1

It is important to consider what customizations have been performed on the site since the last update and the readiness of the site's custom code to switch to another version of php, since the current version of Bitrix requires the current version of php.
Procedure and things to consider:
1. Activate the license on the main version of the site without installing updates.
2. Deploy a test copy of the site on the site with the settings corresponding to the main site
. 3. Check the "Quality Monitor" for modification of the Bitrix core files.
3.1. If modifications are found, check that this is a custom code that is needed for the project to work and written in an invalid place or a false positive of the site verification tools.
3.2. Move the identified custom code to the correct place - separate components or handler files where this code will not be overwritten during the update.
4. On a test copy, upgrade to 17.1 or 17.5. At this stage, the first difficulties can be identified.
4.1. The checkout components are moving to the new API, and if there are custom handlers in the checkout templates, errors will be detected.
4.2. Serious changes in working with JS Bitrix also need to check the readiness of the site to work with the new JS
5. Convert the database tables of the online store and switch to the D7 core.
6. Most likely there will be problems in the checkout functionality. You can temporarily switch checkout to legacy API compatibility mode.
7. If 1C was connected to the site, payment services, delivery services - at this stage they will be abandoned, since the format of Bitrix with payments has changed.
8. If everything works, update Bitrix to 18.1 and check the functionality
9. Switch the site to php 7.0 (you can immediately to php 7.1, but it is better to solve problems in stages)
10. After switching the php version, check the correctness of the custom code on the new version and, if necessary rewriting the code to be compatible with the current version of php
This is a common scenario. Each case is individual and the labor costs for the task depend on the quality of the site development, the quality of the custom code. But even with correct development, with such a significant update, many third-party modules installed on the site will require further development or at least an update.
The task may require from 10 hours. up to 200 hours or more. It depends on the quantity and quality of the custom code (on the size of the project's technology debt). In some cases, all the "crutch" custom code has to be processed into modules and components.
The most neglected case that I have met is a technological debt of 500-600 hours.
it was decided to launch a new project and gradually implement all custom functionality correctly in it without losing the ability to install updates.
Do not launch your projects - make sure that the technical specialists, when performing the task, comply with the Bitrix requirements for implementations and retain the ability to install updates.

Answer 2

In your case, this is not about updating, but about creating a new version of the site on a new license. There is no downgrade in Bitrix, i.e. license downgrade. You will not be able to enter a new key in place of the old one.
You need to create a new version of the site on a subdomain in utf-8, on PHP version 7.1, activate a new license on the new site, transfer all the structure and data from the old site, and then either change sites or redirect the domain (A-record)