Before you start¶
Before starting the upgrade check your system for compatibility with a newer TYPO3 version.
- Enable the deprecation log and let it run for a while while the website is used to catch all deprecations
- Check installed extensions for versions compatible to the target TYPO3 version
- Try the upgrade on a development system first!
TYPO3 promises a certain amount of backwards-compatibility between versions:
- Minor versions are always backwards-compatible
- Major versions may contain breaking changes - normally these are deprecated in the version before
Here is an example. If the TYPO3 team decides that an API method is no longer useful and should be removed they will first add a deprecation notice for the next major version and will remove that method only in the major version after that. So for example a method getting deprecated in version 9 will only be removed in version 10.
This methodology gives you one major version (usually 1 1/2 years) advance notice of any changes you need to make to your code to stay compatible to coming TYPO3 versions.
If you notice some API you are using is deprecated, you should look up the corresponding changelog entry and see how to migrate your code corresponding to the documentation.
Read where to find deprecation documentation in the chapter about Check the ChangeLog.