Cannot Input Payment

I’m having an issue with my install where when I try entering a client payment - either the full balance or even a partial - I get the following error:

The amount must be less than {$invoice->balance}

That message appears under the amount field.

Any assistance is appreciated.

This has been fixed in our latest release.

https://www.invoiceninja.com/self-host/

You can manually fix it by changing the single quotes to double quotes in the following line in app/Http/Requests/CreatePaymentRequest.php

        'amount' => 'required|less_than:{$invoice->balance}|positive',

To

        'amount' => "required|less_than:{$invoice->balance}|positive",