Projeto Gestão de Associados - consultas cobrança

Solicito proposta para o desenvolvimento especificado no documento anexado a este projeto.
Junto a isso, ver o problema do link http://www.apasp.net.br/hml/sga/, a causa e solução.

Fatal error: Uncaught Error: Call to undefined function Symfony\Polyfill\Mbstring\iconv_strpos() in /home2/apasp072/public_html/hml/sga/projhomolog/vendor/symfony/polyfill-mbstring/Mbstring.php:490 Stack trace: #0 /home2/apasp072/public_html/hml/sga/projhomolog/vendor/symfony/polyfill-mbstring/bootstrap.php(34): Symfony\Polyfill\Mbstring\Mbstring::mb_strpos(null, '/json', 0, 'utf-8') #1 /home2/apasp072/public_html/hml/sga/projhomolog/vendor/laravel/framework/src/illuminate/support/str.php(103): mb_strpos(NULL, '/json') #2 /home2/apasp072/public_html/hml/sga/projhomolog/vendor/laravel/framework/src/Illuminate/Http/Concerns/InteractsWithContentTypes.php(34): Illuminate\Support\Str::contains(NULL, Array) #3 /home2/apasp072/public_html/hml/sga/projhomolog/vendor/laravel/framework/src/Illuminate/Http/Request.php(339): Illuminate\Http\Request->isJson() #4 /home2/apasp072/public_html/hml/sga/projhomolog/vendor/laravel/framework/src/Illuminate/Http/Request.php(367): Illuminate\Http\Request->getInputSource() #5 /home2/apasp072/pub in /home2/apasp072/public_html/hml/sga/projhomolog/vendor/symfony/polyfill-mbstring/Mbstring.php on line 490