> ## Documentation Index
> Fetch the complete documentation index at: https://docs.lasso.sh/llms.txt
> Use this file to discover all available pages before exploring further.

# Block regression protection

> Keep successive latest-block responses from going backwards.

Turn **Block regression protection On** in your custom profile's chain settings.
Lasso protects successive latest-block responses and automatically shares
progress across its servers. **Off** is the default.

Applies to:

* `eth_blockNumber` with `[]`.
* `eth_getBlockByNumber` with `["latest", false]` or `["latest", true]`.

## What to expect

After a protected response returns block 100, the next request on the same
running Lasso server returns **100 or higher, or an error**, even if the upstream
provider changes. The next request must start after the previous response
finishes; overlapping requests can finish out of order.

All callers using the same profile and chain share this protection. After a
server switch or restart, recovery is **best effort**: a lower height remains
possible.

Provider lag, stale blocks or reorganizations can cause retries or errors.
Retries and connection setup can add latency. Protected blocks must be within
**60 seconds or four configured block intervals**, whichever is greater;
protection does not promise the newest block or finality.

## Reading state

Ordinary `latest` balance and contract calls remain unpinned. Explicit block
targets stay unchanged through retries, including older blocks. To read several
values at one block, follow [Read at one block](/cloud/read-at-one-block); that works
with protection Off too.

[Routing metadata](/cloud/observability#block-protection-metadata) is optional.
Existing `global` profiles retain strict fleet coordination until disabled;
turning protection On again enables the standard behavior above.