Simple php issue fix

Need to fix the small code issue in php Warning: array_key_exists() expects parameter 2 to be array, null given in /home/***/[login to view URL] on line 131 Warning: Cannot modify header information - headers already sent by (output started at /home/***/[login to view URL]) in /home/***/[login to view URL] on line 152 Here are the snippet of the code line 131 elseif(array_key_exists($j, $json)){ Here is the snippet of the code line 152 header("Location: [login to view URL]"); Full codes will be provided later Currently the script is doing below curl -u username:password -X GET https://***.com/abc/k1/gnv?msisdn=+4444455443 accept the csv with up to 100 entries and do the backend query and give the list with the result back with csv or web display so now we want to add option for the script to accept web interface for the only unumber mobile number then display the result on web interface insted in addition to current csv here is the snippet for the line 131 elseif(array_key_exists($j, $json)){ and snippet of line 152 header("Location: [login to view URL]"); This simple script is used to connect a simple API by uploading the csv content of the mobile numbers we also want have a we interface to input the mobile number and show the result on web interface for up to 3 mobile numbers