The iconv is installed by default (compiled) in current versions, but it may be that eventually the PHP has been compiled using flag --without-iconv, if this is the case and you don’t have access to the server to reinstall PHP, you can install "polyfill" to Symfony using composer:
Navigate to the project folder:
cd /home/gabriel/NetBeansProjects/CasaDoGesso
Type this (you have to have the composer installed):
composer require symfony/polyfill-iconv
Repository: symfony/polyfill
Other polyfills for Symfony
Install as needed using composer require
symfony/polyfill-apcu to use the functions apcu_
symfony/polyfill-php54 to use PHP 5.4 functions in previous versions
symfony/polyfill-php55 to use PHP 5.5 functions *
symfony/polyfill-php56 to use PHP 5.6 functions *
symfony/polyfill-php70 to use PHP 7.0 functions *
symfony/polyfill-php71 to use PHP 7.1 functions *
symfony/polyfill-iconv to use the functions of iconv
symfony/polyfill-intl-grapheme to use the functions grapheme_*
symfony/polyfill-intl-icu to use functions and classes intl
symfony/polyfill-intl-normalizer to use the functions intl normalizer
symfony/polyfill-mbstring to use the functions mbstring
symfony/polyfill-xml to use the functions utf8_encode and utf8_decode
symfony/polyfill-util utilities for "polyfill"
If you need (I think very unlikely) you can install all at once:
composer require symfony/polyfill
Correction: Function and non-method...
– Wallace Maxters