Please help me
Exactly what did you do that triggered the error? Troubleshooting is difficult without information.
But all internal errors indicate bugs, so I am moving this topic to the bugs category.
while creating new invoice the issue creating a problem
When I said “exactly” I meant exactly. “While creating new invoice” is not helpful. Describe the specific steps you had taken and the action that caused the error message to appear. You cannot expect anyone to guess what you did.