How to fix the error “Matomo is unable to write to some directories”?

This error can usually be resolved by executing the commands shown in the error message in the Matomo UI, for example:

If your web server username is www-data then you can have your webserver own the files in this directory (replace www-data by the web server username, sometimes called apache):

sudo chown -R www-data:www-data /path/to/matomo/*

If your server is running SELinux or CentOS, you may be able to fix the issue with the following commands:

chcon -R -t httpd_sys_rw_content_t /path/to/matomo
semanage fcontext -a -t httpd_sys_rw_content_t "/path/to/matomo(/.*)?"

(Replace /path/to/matomo with the path to the Matomo directory)