# 54205: Map Item revision mismatch

Log Level: ERROR

## Description

The actual revision of the Map Item does not match the expected revision.

### Possible causes

* Your update to this Sync Map Item has conflicted with a request submitted elsewhere.
* The value specified in the If-Match header is erroneous.

### Possible solutions

If your update conflicts with a concurrent update elsewhere, the correct solution is to read the latest data (on the client SDK: wait for an update) and then re-attempt your update until you succeed. Consider that, since the data has changed, you may not want to submit the exact same update a second time. On the JavaScript SDK, we suggest using the [mutate](/docs/sync/mutation-and-conflict-resolution#javascript-sdk-conflict-walkthrough) convenience function.

The value you provide in the If-Match header should be a revision assigned by the Sync service when interacting with the object.

* In SDKs, this is the `revision` field, part of the object descriptor.
* When using REST (e.g. via the Twilio Helper libraries) this is the `ETag` header provided in responses.