Upgrading to PHP 7 on Debian Sid with WordPress and Tiny Tiny RSS

After doing a dist-upgrade I have PHP7 installed. WordPress itself didn’t immediately break, but wp-cli did:

“Your PHP installation appears to be missing the MySQL extension which is required by WordPress.”

To fix that I had to install the php7.0-mysql package.

I hadn’t updated Tiny Tiny RSS since it moved off of GitHub, so I had to update its URL:

git remote set-url origin https://tt-rss.org/gitlab/fox/tt-rss.git

After that I had to do the normal database upgrade by loging in as admin. But then trying to run update_daemon2.php gave the following errors:

PHP Fatal error: Uncaught Error: Call to undefined function mb_internal_encoding() in /var/www/ttrss/include/functions.php:19
Stack trace:
#0 /var/www/ttrss/include/autoload.php(2): require_once()
#1 /var/www/ttrss/update_daemon2.php(12): require_once(‘/var/www/…’)
#2 {main}
thrown in /var/www/ttrss/include/functions.php on line 19

To fix that error I installed the php7.0-mbstring package.

I was then greeted with this error:

Tiny Tiny RSS was unable to start properly. This usually means a misconfiguration or an incomplete upgrade.
Please fix errors indicated by the following messages:

* FEED_CRYPT_KEY requires mcrypt functions which are not found.
* PHP support for DOMDocument is required, but was not found.

You might want to check tt-rss wiki or the forums for more information.
Please search the forums before creating new topic for your question.

These dependencies were fixed by installing the php7.0-mcrypt and php7.0-xml packages.