Decrypting: authentication error when using the encryption library

Hello friends,

I am currently trying to use the encryption library on Codeigniter 4 (I am not using it for passwords   ). When i use the $this->encrypter->encrypt($var) , it seems to work, cus I don't get any errors and I get what seems like gibberish in my database as I would want to. 

However , when I fetch the encrypted data and try to decrypt I get this error :  "Decrypting: authentication error" . Below are my codes.

Encryption config file

Code:

public $key = 'secret key';

Constructor to initialize service

Code:

public function __construct()
  {
$this->encrypter = \Config\Services::encrypter();

}

Decrypting: authentication failedDecrypting: authentication failed
Encrypting data

Code:

$this->encrypter->encrypt($var)

Decrypting: authentication failed
Decrypt data

I tried both

Code:

<?=$encrypter->decrypt($var);?>

and

Code:

<?=$encrypter($var,$key);?>

Yet I was still getting errors, Any help is appreciated.

Regards. 
Decrypting: authentication failedDecrypting: authentication failed