What causes "Unable to connect find mapped value with name '{0}'." in pentaho/pentaho-kettle?

Open the Mapping step settings in the parent transformation and correct/remove the field mapping whose source field no longer exists.

pentaho/pentaho-kettle · error · KettleStepException

MappingInput.Exception.UnableToFindMappedValue

MappingInput.Exception.UnableToFindMappedValue

Error message

Unable to connect find mapped value with name '{0}'.

What it means

During the first pass of processRow, the Mapping Input step applies the configured field renames (MappingValueRename) to its output row metadata. If a rename spec references a source field name that does not exist in the incoming row metadata, this KettleStepException is thrown. It signals a mismatch between the mapping's field-mapping definition and the fields actually produced by the parent transformation.

Solutions

Open the Mapping step settings in the parent transformation and correct/remove the field mapping whose source field no longer exists.
Regenerate the field mappings: re-select the sub-transformation so fields are re-scanned from the actual output.
Verify the upstream step in the parent transformation still produces the expected field (check its output preview).
Check field name spelling/case in the MappingValueRename definitions.

Example fix

// before: stale rename in mapping spec
new MappingValueRename("old_amount", "amount");
// after: match the actual upstream field name
new MappingValueRename("amount_in", "amount");

Defensive patterns

Strategy: validation

Validate before calling

RowMetaInterface upstream = parentTrans.getStepFields(mappingSourceStepMeta);
for (MappingValueRename r : valueRenames) {
  if (upstream.searchValueMeta(r.getSourceValueName()) == null) {
    throw new IllegalStateException("Field not produced upstream: " + r.getSourceValueName());
  }
}

Type guard

boolean fieldExists(RowMetaInterface rowMeta, String name) { return rowMeta != null && name != null && rowMeta.searchValueMeta(name) != null; }

Try / catch

try {
  trans.waitUntilFinished();
} catch (KettleStepException e) {
  if (e.getMessage().contains("Unable to connect find mapped value")) {
    // parse field name from message, fix Mapping step field mappings
  }
  throw e;
}

Prevention

Re-generate mapping field definitions after any upstream field rename/delete.
Preview upstream step output before finalizing mapping parameters.
Keep field names consistent (case, whitespace) between parent and sub-transformation.
Use the 'Get Fields' button in the Mapping dialogs instead of typing names.

When it happens

Trigger: data.outputRowMeta.searchValueMeta(valueRename.getSourceValueName()) returns null while iterating data.valueRenames — i.e., a MappingValueRename whose sourceValueName is absent from the parent's row layout.

Common situations: Parent transformation's field layout changed (renamed/deleted a field) after the mapping definition was saved; wrong hop wired into the Mapping step; copy-pasted mapping parameters pointing at stale field names; case-sensitive field name mismatches.

Understand the failure class

Background: 'Could not be found', 'does not exist', 'not found in database': the resource-not-found family when an ID, slug, key, or URI lookup comes back empty — this error's family across 20 libraries.

Related errors

AI-assisted analysis of pentaho/pentaho-kettle@f3058517a1 (2026-09-13). Data as JSON: /api/errors/8dd730491213e5e4. Report an issue: GitHub.

Appendix: source

Thrown at engine/src/main/java/org/pentaho/di/trans/steps/mappinginput/MappingInput.java:115

      // The Input RowMetadata is not the same as the output row meta-data.
      // The difference is described in the data interface
      //
      // String[] data.sourceFieldname
      // String[] data.targetFieldname
      //
      // --> getInputRowMeta() is not corresponding to what we're outputting.
      // In essence, we need to rename a couple of fields...
      //
      data.outputRowMeta = getInputRowMeta().clone();

      // Now change the field names according to the mapping specification...
      // That means that all fields go through unchanged, unless specified.
      //
      for ( MappingValueRename valueRename : data.valueRenames ) {
        ValueMetaInterface valueMeta = data.outputRowMeta.searchValueMeta( valueRename.getSourceValueName() );
        if ( valueMeta == null ) {
          throw new KettleStepException( BaseMessages.getString( PKG, "MappingInput.Exception.UnableToFindMappedValue",
              valueRename.getSourceValueName() ) );
        }
        valueMeta.setName( valueRename.getTargetValueName() );

        valueMeta = getInputRowMeta().searchValueMeta( valueRename.getSourceValueName() );
        if ( valueMeta == null ) {
          throw new KettleStepException( BaseMessages.getString( PKG, "MappingInput.Exception.UnableToFindMappedValue",
              valueRename.getSourceValueName() ) );
        }
        valueMeta.setName( valueRename.getTargetValueName() );
      }

      // This is typical side effect of ESR-4178
      data.outputRowMeta.setValueMetaList( data.outputRowMeta.getValueMetaList() );
      this.getInputRowMeta().setValueMetaList( this.getInputRowMeta().getValueMetaList() );

      // The input row meta has been manipulated correctly for the call to meta.getFields(), so create a blank
      // outputRowMeta

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