How To Fix IO401 - A character string has not been entered

IO401 - Overview

• Message type: E = Error

• Message class: IO - Plant Maintenance: Object List

• Message number: 401

• Message text: A character string has not been entered

What causes this issue?

Program error

System Response

The system does not allow further processing.

How to fix this error?

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Error message extract from SAP system. Copyright SAP SE.

IO401 - Details

• The SAP error message IO401, which states "A character string has not been entered," typically occurs when a required field in a transaction or program is left blank or not filled out correctly. This error can arise in various contexts, such as during data entry, configuration, or when executing certain transactions.
  Causes:
  
  Missing Input: A mandatory field that requires a character string (like a name, description, or identifier) has not been filled in.
  Incorrect Field Type: The system expects a character string but receives an incompatible data type (e.g., numeric).
  Validation Rules: Custom validation rules or enhancements may be enforcing stricter checks on input fields.
  User Authorization: Sometimes, the user may not have the necessary permissions to enter data in certain fields.
  
  Solutions:
  
  Check Required Fields: Review the transaction or screen where the error occurred and ensure that all mandatory fields are filled in with appropriate values.
  Data Type Verification: Ensure that the data being entered matches the