Error: Invalid media box

I'm trying merge a lot of pdf files and it only says:
```
merge2pdf_windows-386.exe -s A4 --scale-width  20240913.pdf C:\Users\Administrator\Desktop\test\20240913
Error: Invalid media box (C:\Users\Administrator\Desktop\test\20240913)
```

I don't know why and which pdf has a problem.
I have to manually figure it out among the hundreds of file. 

Is there any way to help this out?