Upgrade from Horde 5 / PEAR
Horde 5 is supposed to run on PHP 5.x - 7.4 and Horde 6 is supposed to run on PHP 7.4 - 8.x.<br />
Also, the filesystem structure of Horde 6 is different. It is recommended NOT to run an inplace upgrade but backup all assets and start
Prerequisites
- Copy existing installation's database to a new database. At the end of the installation the schema will be changed and no longer fit for Horde 5.
- Go to all Horde 5 apps, including horde base, and safe files like
    - registry.local.php
    - conf.php
    - prefs.local.php
    - hooks.php
    - attributes.local.php
    - backends.local.php
    - basically *.local.php
    - registry.d/*
You normally don't need to keep these:
- conf.xml
- prefs.php
- backends.php
- attributes.php
These come with the code.<br />
Modifying these was not advisable even in horde 5.
Web Server Config
The Web server's webroot needs to point to the /web subdirectory of the root project, not the top directory of the root project.<br />
See fresh install docs for more detail.
Setup a root project
<pre><code>
git clone https://github.com/maintaina-com/horde-deployment.git
</code></pre>
Copy Horde configs
Mind the different structure:
<pre><code>
old: horde/config/conf.php
new: var/config/horde/conf.php
old: horde/config/*.local.php
new: var/config/horde/
old: horde/config/registry.d
new: var/config/horde/registry.d/

old: horde/nag/conf.php
new: var/config/nag/conf.php
old: horde/nag/config/*.local.php
new: var/config/nag/*.local.php

etc
</code></pre>
Editing registry
If your registry.local.php or registry.d/ snippet contains hardcoded webroot or fileroot, comment out these lines.
Install Horde 6
Install the base app
<pre><code>
composer install
</code></pre>
Install additional apps
<pre><code>
composer require horde/kronolith ^5
composer require horde/turba ^5
composer require horde/passwd ^6
composer require horde/mnemo ^5
composer require horde/content ^3
composer require horde/timeobjects ^3
composer require horde/imp ^7
composer require horde/nag ^5
composer require horde/activesync v3.0.0.alpha4
</code></pre>
etc ... see the installing chapter for more details on this step.
Upgrade the database
<pre><code>
./vendor/bin/horde-db-migrate up
</code></pre>
Check the Web UI for configs that need upgrading
Goto the horde/admin/config screen. Check for all apps if there are new settings which need configuration.