Hi Narsa,
I hope the error is not from MM01 T-code, the error is inside BDC program. Are you reading the value from application server. If so, kindly check the following,
- The issue may be due to don't have authorization
- File may be corrupted
- File name wrong
- Check Filename Case Sensitive(Lower/Upper case)
Regards
Rajkumar Narasimman