# event-hash-malformed

The **hash** of an anchor is **not a valid hash**.

- **Routes:** `create-backup` and `audit-history`
- **Description:** `event hash is malformed: expected 64 lowercase hexadecimal digits, prefixed with 'esdb:hash:v2:' for a hash of version 2`
- **Details:** **`value`**, the hash as the request gave it.

## Why It Happens

The `hash` of an anchor, **`lastBackedUpEvent`** for an incremental **[backup](/docs/eventsourcingdb/backup-and-restore)** or **`lastAuditedEvent`** for an **[audit](/docs/eventsourcingdb/auditing-the-event-store)**, is the hash of an event as EventSourcingDB answered it: **64 lowercase hexadecimal digits**, with the prefix `esdb:hash:v2:` for a hash of version 2, and without a prefix for a hash of version 1, which predates it. A hash with **uppercase digits**, one that is cut short, or one with another prefix is refused.

## How to Fix It

Send the hash **exactly as EventSourcingDB answered it**, without changing its case or cutting it. Sending the same request again fails the same way.

## Example

For an audit whose `lastAuditedEvent` has the hexadecimal digits of its hash in uppercase, EventSourcingDB answers with this error, as a line of the stream, and then ends the stream with its `end` item:

```json
{
  "type": "error",
  "data": {
    "code": "https://docs.eventsourcingdb.io/errors/event-hash-malformed",
    "description": "event hash is malformed: expected 64 lowercase hexadecimal digits, prefixed with 'esdb:hash:v2:' for a hash of version 2",
    "details": {
      "value": "esdb:hash:v2:5ED0A363267D554F75EE284F444FCAAC46C1956D5BC24A2AFF21AB120C028702"
    }
  }
}
```