## TL;DR
Zero conversion is a setup smell: trials end, but the conversion charge fails for everyone (no payment method collected, wrong price id, tax or region block) or conversions happen and are not recorded. Follow one ended trial through the billing system and see what the system attempted at trial end.

```text
trial conversion dropped to zero: billing setup error
```

## Use this when
- Trials still start and end normally but conversions read zero
- Trial volume is unchanged from healthy periods
- A pricing, price-id, or checkout change shipped near the drop

## Not for this skill when
- Signups shifted to a low-intent channel at the same time
- Conversion fell by half, not to zero, suggesting offer or audience change

## Steps
1. List trials that ended in the last 7 days and their billing status now. Verify: each ended trial shows converted, past due, cancelled, or stuck, with counts
2. For stuck or failed ones, read the exact billing error: missing payment method, declined, wrong price, or tax block. Verify: the dominant failure code is identified
3. Check the trial signup flow for the payment-collection step and the plan-to-price mapping in the current build. Verify: the setup defect (skipped collection, stale price id) is pinpointed
4. Fix it, then retry conversion for recoverable ended trials with customer notice. Verify: recoverable trials convert or decline with a clear customer message
5. Add a daily trials-ended versus trials-converted check with a zero-conversion alert. Verify: a repeat pages within a day instead of a month-end surprise

## Variant phrasings
### trial conversions zero
A related phrasing for the same underlying problem.
### trial end billing failure
A related phrasing for the same underlying problem.
### trials not converting after pricing change
A related phrasing for the same underlying problem.

Compatibility: Compatibility: trial flows on Stripe Billing or Chargebee with product signup instrumentation, current versions.

## Why it happens
Markets do not produce exactly zero conversions; configurations do. The billing status distribution of ended trials is the fastest evidence: it separates never-attempted (setup) from attempted-and-declined (customer) in one query.

## Edge cases / pitfalls
- Some trials are sales-assisted and convert by invoice offline. Exclude them before declaring zero, or the metric mixes two motions.
- Price-id mistakes often affect one plan or region only. Split the zero by plan before fixing globally.
- Retrying conversions days later without notice creates surprise charges and disputes. Notice first, charge second.

## Provenance

Resolved from the public thread: https://vectle.com/posts/pst_qeJNwT6mtFPzG1tXbAcdWQ