ERR_LOOKUP_FAILED on Airtable: Lookup table lookup failed. Root cause: The lookup formula references a field value that doesn't exist in the linked table, or the record ID has changed since the automation was built. This commonly occurs when records are deleted, renamed, or when the lookup field targets a view that has been filtered. Step 1: Understand the difference between a Lookup field and a LOOKUP() formula. Airtable has two lookup mechanisms that fail in different ways. A Lookup field (created via the field type menu) pulls values from a linked record and breaks when the linked record is deleted or the linked field is renamed. A LOOKUP() formula function fails when the first argument (the linked record field) returns no records. Identify which type you are using before troubleshooting. Step 2: Check whether the linked record still exists. Open the record with the failing lookup. Click the linked record field — if it shows a grey "Record deleted" placeholder or is empty, the source record was deleted. Lookup fields cannot return data from deleted records. You need to either restore the deleted record (Airtable keeps deleted records for 7 days on Pro plans: go to the table → click the recycle bin icon in the top right) or update the link to point to an existing record. Step 3: Verify the source field has not been renamed or changed type. Lookup fields are bound to a specific field name in the linked table. If someone renamed the source field (e.g., "Status" was renamed to "Deal Status"), the lookup field loses its binding and returns blank. Go to the linked table → find the field your lookup references → confirm its name matches what the lookup field is configured to pull. To fix: click the lookup field → Edit field → reselect the correct source field from the dropdown. Step 4: For LOOKUP() formula failures, check the view filter. LOOKUP() searches across all records in the linked table by default, but if your linked record field is filtered to a specific view, LOOKUP() only searches within that view. Records outside the view are invisible to the formula. Go to the linked table → check whether the view being used has any filters applied — specifically filters that might exclude the records you are trying to look up. Step 5: Handle empty lookup results gracefully in formulas. If your lookup is used inside another formula and the lookup returns blank, the outer formula may error. Wrap your lookup in an IF() check: IF(lookup_field = "", "No data", lookup_field). For LOOKUP() functions, use IFERROR(LOOKUP(...), "Not found") to return a fallback value instead of an error. Step 6: For automation-triggered lookup failures, add an error handler. If an Airtable automation uses a lookup field and the lookup returns blank, the automation may fail silently or send incorrect data downstream. In the automation editor, add a Conditional step after the lookup: if [lookup field] is empty, send a notification or log the record ID to an error table. This creates an audit trail of lookup failures without stopping the automation.