ID:12014 Net "<name>", which fans out to "<name>", cannot be assigned more than one value

CAUSE: In a design file, you assigned more than one value to the specified net. You can assign only one value to the net. The submessages of this message indicate the signals with values assigned to the net.

ACTION: Ensure the design file contains only one assignment to the net. If you are using Incremental Compilation and this error is occurring along a partition, the design likely is distributing tri-state logic across partitions. In that case, redesign your modules so all tri-state logic is within a single partition(preferably the topmost partition).