Have you printed out your JSON data string at the receiving end to see what you get there? An empty string gives the same error message:

>perl -MJSON -e "print JSON->new->decode('')"
malformed JSON string, neither array, object, number, string or atom, 
+at character offset 0 (before "(end of string)") at -e line 1.
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I think you are trying to pass the data around in a very bad manner:

If you send POST data, please read HTTP::Request on how to send POST data. If you want to send the data in an URI, please encode it properly using URI::Encode.

mo luck!! tried like this:

my $inData = { "name" => "test", "id" => "test", "test" => [1,2,3,4],}
+;
my $json   = JSON->new->utf8->allow_nonref;
my $jsonData = $json->encode($inData);
print Dumper($jsonData);
##Output of dumper : 
$VAR1 = '{"test":[1,2,3,4],"name":"test","id":"test"}';

# post set post request
my $req = HTTP::Request->new('POST', $rest_url);
$req->content($jsonData);
my $response  = $iua->request($req);
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getting same error.

Where did you try what?

I think that you are either not sending the data you think you're sending, or you're not receiving the data you think you're receiving. You have not shown working, self-contained code that exhibits the problem, so it's hard to replicate your problem or to understand what you're doing wrong.

If you want to investigate this further, I suggest printing the values you get in the request to a log file on the receiving end.

This error message occurs when you pass the empty string or an undefined variable to be decoded by JSON, JSON::PP or JSON::XS.

So I'd suggest that even with the updated code, the problem is related to the initialization of $jsonText - it appears to be undef.