This error may occur either when editing in Spatial Manager or when using locator with different product-specific forms. The following is an example of an error message when trying to send a TMA notice:
tma-0093 unable to send notice, error in API (tma_works_api.process_pase_coords) domain index is marked LOADING/FAILED/UNUSABLE
The spatial index in one or more spatial tables has been invalidated.
Run the following script to determine which spatial tables have the invalid index:
select index_name, table_name, owner, status, DOMIDX_status, domidx_opstatus from all_indexes where DOMIDX_opstatus is not null and DOMIDX_opstatus != 'VALID';
This will return a list of table and index names eg.
In this example, the error was displayed when working with TMA, so the most likely culprit(s) are the TMA tables (TMA_PHASES_SDO and TMA_NONSWA_STR_LOCS_SDO)
In order to recreate the index go to the GIS Layer tool form, get this table and press the [Rebuild Index] button as shown in the screenshot below.