
This means that you have attached walls to, for instance, a roof or a floor and then the target has moved so that the wall can't attach anymore. Highlighted walls are attached to, but miss, the highlighted targets. Revit does not like these lines, and both performance and stability issues might occur - you can of course make walls with an angle in Revit, just not such a small angle. This is a common warning and important to fix - an off axis wall might be difficult to dimension and an elevation towards such a wall has been known to cause instability issues in the past. Use the Naviate Align Walls function to realign the wall or all walls in your project.

Draw a line and use the Align tool to align the wall to the line.Redraw the wall and make sure to snap correctly - that is, do not snap an endpoint.There are a few different ways to correct the error:

It can also occur when you join to walls that were almost inline. It can occur when if you have modelled walls from an underlaying DWG-file which is not as straight as Revit would prefer, or when you have rotated the project against such a line. This error occurs when walls are almost 45º, 90º or 0º to the internal coordinate system - the off-angle is usually very small, about a thousands of a degree. Walls are slightly off axis and may cause inaccurances.
