Give write permission (usually 755) to config/, storage/ and public/uploads/ using your hosting file manager or FTP.
mod_rewrite is off or .htaccess is not read (AllowOverride). Check that the .htaccess files were uploaded and ask your host to enable mod_rewrite and AllowOverride All.
Error details are not shown to visitors. Check storage/logs/app-DATE.log. A common cause is a PHP version below 7.1 or a missing extension.
The file is over 5 MB, not JPG/PNG/GIF/WebP, or public/uploads/ is not writable. Also check PHP's upload_max_filesize and post_max_size.
HTML is not accepted for security reasons. Use the simple format (see "Creating pages and posts").
Not in 1.1.0: only the interface is in three languages. Content is written in a single language.
Member sign-up and profiles exist (1.1.0); there is no forum, shop or roles such as 'editor'. 1.1.0 is a minimal CMS: pages, news/posts, categories, media, menu, SEO and a three-language interface. For a forum, use the forum on MyWap.az.
Back up first, then delete storage/installed.lock and config/config.php manually and use an empty database.
Run the installer from the subfolder (/folder/install/); the address is detected automatically. If you moved the site later, fix base_url in config/config.php.
Use the MyWapCMS board on the MyWap.az forum.