QuickBooks Error H101 occurs when attempting to access company files located on another computer, and the server setup needs additional configuration. This error can disrupt the multi-user connection to the server, making it challenging to access vital financial data. It typically arises due to incorrect hosting configuration settings, firewall blockages, or issues with the DNS server. Addressing this error involves checking the hosting settings, configuring the firewall properly, and ensuring that the network data files are correctly set up to allow seamless access and communication.