# Build Errors

The calculation cannot proceed if there is a build error. A build error means that the flowsheet representation of the network is incomplete. There are 3 fundamental reasons that a build error can occur.
1. | A node may have insufficient pipe connections. An example would be a reducer or valve with only one connecting pipe.
2. | Each network, and subnetworks must contain at least one boundary component where the pressure is known or specified. These component are any of the following
3. | A node or pipe may have an identifying name, which acts as a database link to additional component information that is not present in the currently connected database. This will typically occur in a multi-user environment where different users swap files and databases instead of keeping centralized copies of files and databases.
The Messages list containing a build error is shown below. Note the stop icon in the list, the message repeated on the status line, the synchronization between the flowsheet and the messages list and the verbose description of the highlighted list item below the list (in the Description Window).