+## 4.5.0 -> 5.0.0
+
+### PHP frontend removed
+
+The PHP frontend has been completely removed. Please switch to the Python
+frontend.
+
+Without the PHP code, the `nominatim refresh --website` command is no longer
+needed. It currently omits a warning and does otherwise nothing. It will be
+removed in later versions of Nominatim. So make sure you remove it from your
+scripts.
+
+### CMake building removed
+
+Nominatim can now only be installed via pip. Please follow the installation
+instructions for the current version to change to pip.
+
+### osm2pgsql no longer vendored in
+
+Nominatim no longer ships its own version of osm2pgsql. Please install a
+stock version of osm2pgsql from your distribution. See the
+[installation instruction for osm2pgsql](https://osm2pgsql.org/doc/install.html)
+for details. A minimum version of 1.8 is required. The current stable versions
+of Ubuntu and Debian already ship with an appropriate versions. For older
+installation, you may have to compile a newer osm2pgsql yourself.
+
+### Legacy tokenizer removed
+
+The `legacy` tokenizer is no longer enabled. This tokenizer has been superseded
+by the `ICU` tokenizer a long time ago. In the unlikely case that your database
+still uses the `legacy` tokenizer, you must reimport your database.
+
+### osm2pgsql style overhauled
+
+There are some fundamental changes to how customized osm2pgsql styles should
+be written. The changes are mostly backwards compatible, i.e. custom styles
+should still work with the new implementation. The only exception is a
+customization of the `process_tags()` function. This function is no longer
+considered public and neither are the helper functions used in it.
+They currently still work but will be removed at some point. If you have
+been making changes to `process_tags`, please review your style and try
+to switch to the new convenience functions.
+
+For more information on the changes, see the
+[pull request](https://github.com/osm-search/Nominatim/pull/3615)
+and read the new
+[customization documentation](https://nominatim.org/release-docs/latest/customize/Import-Styles/).
+
+## 4.4.0 -> 4.5.0