Maybe because Autodesk has changed the file format, file header (to recognize if this file is a trusted DWG?) or may be because the application is become more and more complex it become more vulnerable. I donвЂ™t know why this never show up before. This problem never occur when he still use his old AutoCAD (i forgot the version) and when he is assigned to another division, using AutoCAD LT 2007, this error starting to show up. A lot of objects can make your file corrupt. This will cause your file become more and more complex. So he open his old file, create his drawing, and delete objects he didnвЂ™t need. And he didnвЂ™t aware about creating a template for this purpose. He was too lazy to redefine all of the styles and settings he needed. I saw an AutoCAD user always create his drawing from his previous drawing. Also try to create a new file from scratch using default templates and see if this still occur. Does this occur on all of your machine? Does this happen when you open a specific file? Try to open your file on different machine, and see if it also cause error there. Eliminate Them!ДЇirst, you have to eliminate the possibilities what cause the error: is it machine specific? Or is it file specific? I think it might be cruel to say it can also human specific, but how people using AutoCAD can cause this. Bugs maybe there, but many times it is not caused by it.

There are a lot of things can cause this. After using and troubleshooting AutoCAD for several years, I found out that itвЂ™s not always AutoCAD problem.

Of course, the first one to blame is AutoCAD.

IвЂ™ve seen a lot of people snapped when their AutoCAD showing the deadly fatal error message.

Fatal error autocad civil 3d 2013