I am testing to install b2evolution in Docker. Using NGINX and PHP-FPM

During install I get the following error after approx. 40% of progressbar
At the end of the installer instead of user and password I see:

Installing sample contents...
Creating Home collection...
Fatal error: Uncaught Error: Call to undefined function ctype_space() in /srv/www/htdocs/vhost1/inc/_core/_misc.funcs.php:558 Stack trace: #0 /srv/www/htdocs/vhost1/inc/_core/_misc.funcs.php(458): strmaxlen('This blog platf...', 254, '&hellip;', 'raw', true) #1 /srv/www/htdocs/vhost1/inc/items/model/_item.class.php(8028): excerpt('This blog platf...', 254, '&hellip;') #2 /srv/www/htdocs/vhost1/inc/items/model/_item.class.php(7999): Item->get_autogenerated_excerpt() #3 /srv/www/htdocs/vhost1/inc/items/model/_item.class.php(7304): Item->update_autogenerated_excerpt() #4 /srv/www/htdocs/vhost1/inc/items/model/_item.class.php(7254): Item->dbinsert() #5 /srv/www/htdocs/vhost1/inc/collections/_demo_content.funcs.php(1244): Item->insert(3, 'About this site', '<p>This blog pl...', '2020-02-07 19:5...', 1, Array, 'published', 'en-US', '', '', 'open', Array, 'Standalone Page') #6 /srv/www/htdocs/vhost1/inc/collections/_demo_content.funcs.php(1111): create_sample_content('main', 1, 3, true, 0) #7 /srv/www/htdocs/vhost1/install/_func in /srv/www/htdocs/vhost1/inc/_core/_misc.funcs.php on line 558

(Webserver output):

web_1  | 2020/02/10 12:42:30 [error] 12#0: *1 FastCGI sent in stderr: "PHP message: PHP Fatal error:  Uncaught Error: Call to undefined function ctype_space() in /srv/www/htdocs/vhost1/inc/_core/_misc.funcs.php:558
web_1  | Stack trace:
web_1  | #0 /srv/www/htdocs/vhost1/inc/_core/_misc.funcs.php(458): strmaxlen('This blog platf...', 254, '…', 'raw', true)
web_1  | #1 /srv/www/htdocs/vhost1/inc/items/model/_item.class.php(8028): excerpt('This blog platf...', 254, '…')
web_1  | #2 /srv/www/htdocs/vhost1/inc/items/model/_item.class.php(7999): Item->get_autogenerated_excerpt()
web_1  | #3 /srv/www/htdocs/vhost1/inc/items/model/_item.class.php(7304): Item->update_autogenerated_excerpt()
web_1  | #4 /srv/www/htdocs/vhost1/inc/items/model/_item.class.php(7254): Item->dbinsert()
web_1  | #5 /srv/www/htdocs/vhost1/inc/collections/_demo_content.funcs.php(1244): Item->insert(3, 'About this site', '<p>This blog pl...', '2020-02-07 05:1...', 1, Array, 'published', 'en-US', '', '', 'open', Array, 'Standalone Page')
web_1  | #6 /srv/www/htdocs/vhost1/inc/collections/_demo_content.funcs.php(1111): create_sample_content('main', 1, 3, true, 0)
web_1  | #7 /" while reading response header from upstream, client: 172.22.0.1, server: vhost1.site, request: "GET /install/index.php?locale=en-US&confirmed=0&installer_version=10&action=newdb&create_sample_contents=1&collections%5B%5D=home&collections%5B%5D=a&create_sample_organization=1&create_demo_users=1&create_sample_private_messages=1&local_installation=1 HTTP/2.0", upstream: "fastcgi://unix:/var/run/php-fpm.sock:", host: "vhost1.site", referrer: "https://vhost1.site/install/index.php?locale=en-US&confirmed=0&installer_version=10&action=menu-install"

The installer does not show me the login credentials. Going to my site shows the site but I don't have the password.
Any ideas what the issue might be?