QuickBooks error H303 can take place while accessing the company file. The error code depicts that your computer requires additional configuration. There can be multi-pronged reasons that can trigger error code H303 in QuickBooks. Poor network, Firewall prevention, damaged.ND files are some of the most apparent reasons behind the error. However, there are several other reasons that can be credited to promote company file access error H303 in QuickBooks. To get all your queries resolved related to QuickBooks error H303, you can give us a call on our QuickBooks error support number (844)-888-4666.