can't upgrade my worksheet

School is starting this week, and I am urgently trying to update one of my existing worksheets. Unfortunately, after I removed the original PDF and uploaded the new one, I was unable to complete the update. The system keeps showing an error message (please see the attached screenshot for details).

Since the original PDF has been removed, the worksheet is currently inaccessible, and the customer link is unavailable. Here is the information about the worksheet:

• Worksheet Title: G3-1-1单韵母和声母（3）

• Worksheet URL: https://www.liveworksheets.com/worksheet/zh/language-arts-vocabulary/8199147

As school starts this week, this issue is quite urgent for my class. I would greatly appreciate it if you could help me look into this and resolve the issue as soon as possible.