Message type: E = Error
Message class:  TI - Treasury: General Messages 
Message number: 020
Message text: Field selection string & is active.
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The SAP error message TI020, which states "Field selection string & is active," typically occurs when there is an issue related to field selection in the context of data entry or configuration in SAP. This error is often encountered in modules like SAP FI (Financial Accounting) or MM (Materials Management) when certain fields are required or restricted based on the field selection settings.
Cause: Field Selection Group: The error indicates that a specific field selection string (group) is active, which means that certain fields are either mandatory, optional, or hidden based on the configuration. Configuration Settings: The field selection settings may not align with the data being entered or the transaction being executed. For example, if a field is set to be mandatory but is not filled in, this error can occur. Transaction Type: The error may also arise if the transaction type being used does not allow certain fields to be filled or
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