Receive error message for radio buttons ."An illegal choice has been detected. Please contact the site administrator."

Question

I have created a multi step form, in which I have added radio buttons dynamically by using data from the database. The radio buttons added here are not required. But still I get the following error. I have created a custom module.

An illegal choice has been detected. Please contact the site administrator.

Kindly help me resolve this issue. This is not a duplicate issue. Other issues listed have mentioned that the radios button are used as required field in that case. Please find the code added :

$opt = array(
        'f' => 'Friend or Business Associate',
        'b' => 'Brochure',
        'c' => 'Company',
        'a' => 'Another Columbia Asia Hospital',
        'ad' => 'Advertisement',
        'an' => 'Another Doctor',

);
$step1['questions']['learn_abt'] = array (
        '#type' => 'radios',
        '#title' => t ( 'In How did you first learn about the Hospital' ),
        '#options' => $opt,


);

Answer 1

I somehow fixed the issue. Normally if it is not a required field we don't need to add the following code.

'#required' => FALSE,

But adding this code fixed my issue. Please let me know if there is any better or correct way to fix this.