Error during field conversion from external to internal format.

What causes this issue?

An error occurred during the attempt to convert a field in the input
file from external to internal format.
Row / column : &V2&
Field contents : &V3&
Dictionary fld : &V4&
Error type : &V1&

System Response

Processing terminates.

How to fix this error?

Check the input file. If it was generated by a standard SAP program,
you may want to contact the SAP Hotline.

Error message extract from SAP system. Copyright SAP SE.