ACA: Ceiling Grid Boundary Selection and Resource Manager Error

That is a pretty scary warning dialog. It makes me think that, at the very least, my AecGuiBase70 file has some form of corruption. If you receive this error dialog while adding a Ceiling Grid and using the Set boundary command option to select a Polyline as the ceiling boundary, your AecGuiBase70 is just fine. The problem is that the Polyline you selected is not a closed Polyline.

"But wait!" you exclaim. "That Polyline looks closed to me." It may very well looked closed, but when drawing the Polyline, merely snapping the last point to the first point does not a closed Polyline make. Next time, stifle the urge to add one more point on top of the first point, and use the Close command option, by selecting it on the Command Line, or by typing C and then pressing the ENTER key.

Fix the already drawn Polyline by using the Close command option of the PEDIT command or by selecting the Polyline and, on the Properties palette, on the Design tab, under the Misc category, set the Closed property to Yes.

BONUS TIP: You can double-click that Polyline to initiate the PEDIT command on that Polyline. Personally, I would get rid of that last vertex and then close the Polyline, but that is not necessary for the Polyline to be a valid Ceiling Grid boundary.

Curiously, the Set boundary option of the CEILINGGRIDCLIP command provides an informative message at the Command line, rather than the non-informative Error dialog the CEILINGGRIDADD command gives, when selecting an open Polyline as the boundary.

The CEILINGGRIDCLIP command is used to add a clipping boundary to an already-placed Ceiling Grid, and can be accessed by selecting the Ceiling Grid and then, on the Ceiling Grid contextual ribbon tab, on the Clipping panel, by selecting the Set Boundary tool.