The signed picture was not uploaded successfully. When using a pdf file, the PDF signature cannot be put into the grid in the file, mostly because the signed picture was not uploaded successfully. The solution is as follows.

1. First, check whether the signed picture was not uploaded successfully due to permission problems.

2. Secondly, check whether it is a network problem.

3. Finally, open the permission of the signed picture, switch the network refresh and put it back in the grid.