There are several reasons for Windows firewall is blocking Quickbooks 2017- when the ports which the application used to access the internet are not forwarded by the computer. QuickBooks doesn’t use a wide range of ports, it uses a specific port depending upon the version of the application that you are using, when the application itself is blocked by the Windows firewall and it is also possible that the third party antivirus might have blocked the application permanently. This error is faced by many users while using Quickbooks software.