File is not found on the server

Hello to all,
I am posting my problem here.
On opening a file stored on a server, I got an error message when I want to access the file. The error message somewhat goes like this, "the file is not found on the server", also check below the error message screen shot.
Message from webpage
File [Y08H1 G000001 SUM.pdf] is not found on the server! Contact the
warehouse administrator.
OK
As I am pondering on the error message, I am wondering why I got this error. I just opened the file a while ago, and I am sure it’s the same file that I am opening now.
Please share some comments and a solution to this scenario that I have.
Many thanks to all.
