I think many of you have come across some unexpected errors for several reasons in the daily design. Here I list some as a start. Since each uses different software, conditions maybe different, my solutions just can be taking as reference. The software exit when you revise your drawings or making other actions. You can open Drawing Utilities from the File on the menu and select Audit to revise. If there are still problems after recovery. Creating a new design environment. First, creating a file and then inserting the file to be revised as a block. Taking notice that changing the coordinate when inserting, for instance, if the original coordinate is (0, 0), changing it to (1, 1). Moving it to the (0, 0) coordinate after inserting. Switching between high version and low version will lead to errors sometimes. Solution to this error is creating a new file with the high version and opening the original drawing. Selecting the Copy with Base Point command from the Edit after selected all the entities. Copying the selected entities to the new file and converts it into low version. When fatal errors come out and need to be revised, we can create a new file and open the file to be revised. Press ESC many times when the file is loading.The following step is inputting Dxfin on the command line. Selecting the exported file and save it after loaded successfully.