A dangling entity in a drawing is an entity that has lost one (or more) of its reference points. Dimensions, section lines, note leaders, callouts, centermarks and geometric tolerances are all examples of entities that could become dangling (broken) after a drawing update. This is to be expected, especially if the change to the part or assembly was significant.
Identifying a dangling entity
A dangling entity is indicated by a red grip point indicating which reference point has been lost.
To fix a dangling entity
Assign a new reference point where one is missing. Click and drag the red grip point away from its location and onto a new reference point.