The following are the errors for the RichTextBox control, located in the RichTx32.OCX file:
| Constant | Value | Description |
| rtfInvalidProcedureCall | 5 | Invalid procedure call. |
| rtfOutOfMemory | 7 | Out of memory. |
| rtfPathFileAccessError | 75 | The specified path/file name cannot be accessed or is invalid. |
| rtfInvalidFileFormat | 321 | Invalid file format. |
| rtfInvalidPropertyValue | 380 | Invalid property value. |
| rtfInvalidPropertyArrayIndex | 381 | Invalid property array index. |
| rtfSetNotSupported | 383 | Property is read-only. |
| rtfSetNotPermitted | 387 | Property cannot be set. |
| rtfGetNotSupported | 394 | Property is write-only. |
| rtfInvalidObjectUse | 425 | Invalid object use. |
| rtfWrongClipboardFormat | 461 | Specified format doesn't match format of data. |
| rtfDataObjectLocked | 672 | DataObject formats list may not be cleared or expanded outside of the OLEStartDrag event. |
| rtfExpectedAnArgument | 673 | Expected at least one argument. |
| rtfFormatNotByteArray | 674 | Non-intrinsic OLE drag and drop formats used with SetData require byte array data. GetData may return more bytes than were given to SetData. |
| rtfDataNotSetInFormat | 676 | Requested data was not supplied to the DataObject during the OLESetData event. |
| rtfInvalidCharPosition | 32000 | Invalid character position. |
| rtfInvalidHdc | 32001 | Invalid HDC. |
| rtfCannotLoadFile | 32002 | Unable to load specified file. |
| rtfInvalidKeyName | 32005 | Invalid or missing key name. |
| rtfInvalidClassName | 32006 | Invalid or missing OLE class name. |
| rtfKeyNotFound | 32007 | Key does not exist. |
| rtfOLESourceRquired | 32008 | Required source document or class name is missing. |
| rtfNonUniqueKey | 32009 | Key is not unique in collection. |
| rtfInvalidObject | 32010 | Invalid object. |
| rtfProtected | 32011 | The operation cannot be performed on protected text. |
| rtfOleCreate | 32012 | Unable to create object. |
| rtfOleServer | 32013 | Unable to start server application. |