During the analysis, the program reports the coordinate information of the problematic node to the developer. You can identify the relevant element or elements by following the coordinate information from the same message. 0:02 ***************************** 0:02 ************* ********* CANNOT SOLVE SYSTEM ON "Modal" LOAD.*********************** 0:02 Pivot error in matrix reduction. 0:02 Problem joint number : 231 0:02 Node coordinates: X : 8.64 Y : 19.10 Z : 6.65 0:02 ************************* ******* 0:02 The analysis has been cancelled. From the coordinate information, it has been determined that a piece of beam as large as the width of the beam in the other direction remains at the end of the cantilever beam ending on the 2nd floor AE axis and that part has been deleted. Similarly, other parts have been deleted, and the error-free version of the project has been added to this message. In order to avoid such problems, it may be necessary to pay attention to the joints of the beam and the floor edge and, if necessary, to replace the beam eccentricities. For example, instead of defining K1-K2 beams from the top, we can define the slab edge-beam nodal points in the same coordinate. Thus, we will not be able to create a piece of beam as small as the width of the beam in the other direction. Good work..