Error changing server

Hello, I’m moving a project from a web server to a local one.
I have configured xampp on the server and everything seems to work fine.
The problem comes when running the project from another computer, when I start the login form and after entering the username I get this error:

     r /> Warning: Undefined array key "charset" in C:\xampp\htdocs\_lib\lib\php\nm_utf8.php on line 32

Warning: Undefined array key "charset" in C:\xampp\htdocs\_lib\lib\php\nm_utf8.php on line 32

Warning: Undefined array key "charset" in C:\xampp\htdocs\_lib\lib\php\nm_utf8.php on line 375

Warning: Undefined array key "charset" in C:\xampp\htdocs\_lib\lib\php\nm_utf8.php on line 377

Warning: Undefined array key "charset" in C:\xampp\htdocs\_lib\lib\php\nm_utf8.php on line 379

Fatal error: Uncaught ValueError: mb_convert_encoding(): Argument #2 ($to_encoding) must be a valid encoding, "" given in C:\xampp\htdocs\_lib\lib\php\nm_utf8.php:79 Stack trace: #0 C:\xampp\htdocs\_lib\lib\php\nm_utf8.php(79): mb_convert_encoding('3', '', 'UTF-8') #1 C:\xampp\htdocs\_lib\lib\php\nm_utf8.php(379): sc_convert_encoding('3', NULL, 'UTF-8') #2 C:\xampp\htdocs\_lib\lib\php\nm_utf8.php(346): NM_charset_decode('3') #3 C:\xampp\htdocs\app_Login\app_Login.php(2054): NM_utf8_urldecode('3') #4 C:\xampp\htdocs\app_Login\index.php(2): include_once('C:\\xampp\\htdocs...') #5 {main} thrown in C:\xampp\htdocs\_lib\lib\php\nm_utf8.php on line 79

Help please.

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