Where it comes from
- Published by Palantir for all engineering rolesSource 1Getting Hired - Palantir CareersPublisherPalantir TechnologiesSource typecompany hiring page More Palantir questions The Palantir interview guide
How to answer
Palantir’s company-wide “Getting Hired” page says its onsite interviewers will ask about where you’ve failed in the past; it does not describe the loop specifically. Source 1Getting Hired - Palantir CareersPublisherPalantir TechnologiesSource typecompany hiring page The wording of this version sets three bars: the fault was yours, the cost was real, and something you do is now different.
Lead with the failure itself, then work through the rest in this order:
- The failure in one sentence, with “I” as the subject. “I pushed an configuration change to the customer’s tenant on a Friday with no rollback plan, and their staff couldn’t log in on Monday.” No setup first.
- The cost, counted. Hours, money, a slipped date, people pulled off other work, and whose cost it was. If the customer paid it, say so.
- The first hour. Who you told, how fast, in what words, and what you did to stop the damage. This is where you show you own things when they break.
- The cause, one level down. Not “I was careless” but the check you skipped or the assumption you didn’t test, and why it seemed safe at the time.
- What you do now. A behavior someone could watch you do, and a later time it caught something.
Say the cause as your action: “I assumed the staging tenant matched production because the same team set both up.” Then stop; don’t add a “but” that moves the fault elsewhere.
Keep the technical cause to a sentence in your first answer. “What would have caught this?” is a likely follow-up, and the query or the missing test is the answer to it.
Pick the story carefully. The failure that is a strength in disguise (“I took on too much”) answers nothing. A failure so large you can’t show it is fixed leaves the listener with the damage and no repair. The right story has a real, bounded cost and a change you can point to.
If you are stuck for one, look for a change you shipped without the check you normally run. Each of these opens with “I” and has a cost someone could count:
- Enterprise software or data: “I ran a schema migration on the customer’s largest tenant without a dry run, and their nightly reports failed for two days.”
- AI product: “I shipped a prompt change without rerunning the evaluation set, and for a week the model refused requests it used to answer on one customer’s main use case.”
- AI search: “I rebuilt a customer’s search index without the permission filter, and for a day staff could see another department’s documents.”
Prepare for the last follow-up, whether the new habit has ever cost you something, before you walk in. A habit that never cost anything sounds made up, so have one time it slowed you down, what it cost, and why you kept it or changed it rather than dropping it.
Follow-ups
What the interviewer may ask next, once your first answer is on the table.
- Who found the problem first, you or the customer?
- What would have caught this before it reached production?
- Has the new habit ever slowed you down enough to cost something, and was it worth it?
Where answers go wrong
- Offers a failure that is really a strength, or spreads the cause across the team and the process, so the “your fault” part of the question goes unanswered.
- Names the cost as “some trust” or “a delay” instead of counting it, and ends with a lesson too general to observe.
Answer this in two minutes
Write the answer you would say out loud. The clock starts with your first word.
Compare with the model answer
Illustrative answer about a fictional project
Written in the first person to show the structure. Tell yours from your own work.
I ran a against a customer’s production ledger with a deduplication key I hadn’t checked, and it merged about 2,300 distinct repayments.
I was building the pipeline that reconciled an equipment lender’s bank repayment files against their loan ledger. I keyed deduplication on the bank’s payment reference because it had been unique in every sample I’d seen.
Two days before month-end close, the controller found a $180,000 gap against the bank statements. Close slipped three days, six of her staff reconciled by hand, and the lender had to explain it to its auditors. She found it before I did. That bothered me more than the bug, because nothing in my pipeline would have told me.
Within the hour I called her: “This is my backfill. I deduplicated on a field that isn’t unique, and I’ve stopped the nightly job.” That evening I deleted only the backfill’s rows, by batch id, leaving everything posted since, and didn’t rerun it. Next morning I confirmed that bank, reference and value date together were unique across all 18 months, wrote the corrected backfill to a shadow table, and had her team approve a row-level diff before we swapped it in.
The cause: my sandbox data came from one of their three banks, and another reuses references. A count grouped by bank and reference over the full table would have shown it; I never ran it.
Now every load asserts that the bank file’s row count and amount total equal what landed in the ledger, and fails loudly if they don’t. That would have caught this in the first minute. At my next customer it failed on day one, on a trailer row loaded as a payment.
It has cost me since. Twice it held a legitimate file of reversals for a morning, because the ledger posts a reversal against the original payment rather than as a new row, so the counts differed by design. I added an expected-reversals input to the check rather than loosen it, because a looser check would let the next silent merge through.