Hi @viranga ,
It means it is temporary network issue during communication. In such situation you (consumer) does not know if the document was accepted (cleared/reported) for sure. Therefore the ONLY solution here is to resubmit the same payload later and get the proper response.
Unfortunately ZATCA experience a lot of such errors and your system should be ready to properly handle such situations. Also your system should not create new payload for the same document as in such situation you can end-up with double submitted documents. This is the example of such situation: Clarification Required for Duplicate Accepted Invoices --HTTP code 111
– Sergei