there are three common solutions to this problem:

the first is to delete the PCB file and create a new one, which is the most unacceptable.

the second way is to delete the CLASS in question, please refer to this article. http://blog.sina.com.cn/s/blog_6b79ac7d0101furd.html

there is another one that I just encountered this time. The problem is that although the schematic diagram encapsulation is drawn in the schematic library, there is no encapsulation when the actual schematic diagram is opened.

the solution is as follows:

1,

dot Update, will prompt you to Update successfully.

2. Update the schematic diagram to PCB

and then we’re done.