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NEWS.md

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+# Cosmos-SDK v0.39.0
+
+This is the inaugural release of the **Cosmos SDK 0.39 «Launchpad»** release series.
+
+## Changes to IAVL and store pruning
+
+The pruning features introduced in the `0.38` release series are buggy and might lead to data loss,
+even after upgrading to `v0.39.0`. When upgrading from `0.38` it is important to follow the instructions
+below, to prevent data loss and database corruption.
+
+**Note: there are are several breaking changes with regard to IAVL, stores, and pruning settings that affect command line clients, server configuration, and Golang API.**
+
+### Migrate an application from 0.38.5 to 0.39.0
+
+The IAVL's `v0.13.0` release introduced a pruning functionality that turned out to be buggy and flawed.
+IAVL's new `v0.14.0` release now commits and flushes every state to disk as it did in pre-`v0.13.0` release.
+The SDK's multi-store will track and ensure the proper heights are pruned. The operator can now set the pruning
+options by passing a `pruning` configuration via command line option or `app.toml`. The `pruning` flag supports the following
+options: `default`, `everything`, `nothing`, `custom` - see docs for further details. If the operator chooses `custom`, they
+may want to provide either of the granular pruning values:
+- `pruning-keep-recent`
+- `pruning-keep-every`
+- `pruning-interval`
+
+The former two options dictate how many recent versions are kept on disk and the offset of what versions are kept after that
+respectively, and the latter defines the height interval in which versions are deleted in a batch. **Note: there are are some
+client application breaking changes with regard to IAVL, stores, and pruning settings.**
+
+### Migrate a node from 0.38.5 to 0.39.0
+
+Note: **do not modify pruning settings with any release prior to `v0.39.0` as that may cause data corruption**.
+The following instructions assume that **pruning settings have not been modified since the node started using 0.38.x. Note: the default pruning setting `syncable` used `KeepEvery:100`.
+
+* The simple upgrade strategy: **perform a full sync of the node from scratch**. Else, follow one of the other strategies.
+
+* If your node had started with using `KeepEvery:1` (e.g. pruning settings `nothing` or `everything`), upgrading to `v0.39.0` is safe.
+
+* Otherwise, do halt block processing with `--halt-height` after committing a height divisible by `KeepEvery` - e.g. at block 147600 with `KeepEvery:100`. The **node must never have processed a height beyond that at any time in its past**. Upgrading to `v0.39.0` is then safe.
+
+* Otherwise, set the `KeepEvery` setting to the same as the previous `KeepEvery` setting (both `<=v0.38.5` and `v0.39.0` default to `KeepEvery:100`). Upgrade to `v0.39.0` is then safe as long as you wait one `KeepEvery` interval plus one `KeepRecent` interval **plus** one pruning `Interval` before changing pruning settings or deleting the last `<=v0.38.5` height (so wait *210* heights with the default configuration).
+
+* Otherwise, make sure the last version persisted with `<=v0.38.5` is never deleted after upgrading to `v0.39.0`, as doing so may cause data loss and data corruption.
+
+## Changes to ABCI Query's "app/simulate" path
+
+The `app/simulate` query path is used to simulate the execution transactions in order to obtain an estimate
+of the gas consumption that would be required to actually execute them. The response used to return only
+the amount of gas, it now returns the result of the transaction as well.
+
+## bank.send event comes with sender information
+
+The `bank.send` event used to carrie only the recipient and amount. It was assumed that the sender of the funds was `message.sender`.
+This is often not true when a module call the bank keeper directly. This may be due to staking distribution, or via a cosmwasm contract that released funds (where I discovered the issue).
+
+`bank.send` now contains the entire triple `(sender, recipient, amount)`.
+
+## trace option is no longer ignored
+
+The `--trace` option is reintroduced. It comes in very handy for debugging as it causes the full stack trace to be included in the ABCI error logs.
+
+## appcli keys parse command didn't honor client application's bech32 prefixes
+
+The `key parse` command ignored the application-specific address bech32
+prefixes and used to return `cosmos*1`-prefixed addresses regardless
+of the client application's configuration.