diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6cf3abcc4f6..f3247b280b5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -24,9 +24,39 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 # [0.9.0]
 
+### Breaking / Migration
+- **Ingest V2 is now the default ingest path.** The `/api/v1/{index}/ingest` endpoint transparently routes to V2.
+- The `rest_listen_port` top-level config field is deprecated; use `rest.listen_port` under the new `rest` block. The old field still works but emits a warning.
+- Stemming is now restricted to the `multilang` cargo feature (#6085); the previously bundled generic stemmer is no longer available by default.
+- The unused multilang tokenizer feature was removed (#6154).
+- Metastore format: new `maturity` field and compaction columns on splits; PostgreSQL metastore migrates automatically on first start.
+
 ### Added
-- Add Ingest V2 (#5600, #5566, #5463, #5375, #5350, #5252 #5202)
+- Add Ingest V2 — now the default (#5600, #5566, #5463, #5375, #5350, #5252, #5202, #6078, #6185, #6203, #6207, #6217, #6249)
+- Offload leaf-search work to AWS Lambda functions — searchers can farm out part of their workload to Lambda (#6157, #5c1e60f)
 - Add SQS source (#5374, #5335, #5148)
+- Add Jaeger v2 support (#6023)
+- Extract and propagate W3C `traceparent` header on incoming HTTP requests (#6224)
+- Support configurable OTLP exporter protocol for traces and logs (#6254)
+- Export internal logs via OTLP exporter (#6142)
+- Add `QW_LOG_FORMAT=DDG` JSON log formatter (#6215)
+- Add ES-compatible endpoints for Trino connector support (#6168)
+- Elasticsearch DSL: prefix and wildcard queries (#6000), `case_insensitive` parameter on supported queries (#6005), regexp shorthand, concatenate-fields exposure, and `text` → `keyword` mapping in `_mapping` (#6208), `index_filter` on field capabilities API (#6102), `ignore_unavailable` query parameter (#5971)
+- Make Elasticsearch `TermsQuery` use `TermSetQuery` internally for better performance (#6151)
+- Add composite aggregation (#6214) and aggregations alias (#6314)
+- Add `skip_aggregation_finalization` to `SearchRequest` (#6145)
+- Add `list_index_stats` endpoint (#6035)
+- Add `validate_docs` ingest setting (#5984); validate doc-mapping updates (#5988)
+- Support updating the doc mapper through the API (#5253)
+- Add CORS debug mode (#5955)
+- Add config to fail search when it targets too many splits (#6009)
+- Differentiate leaf- and root-level search timeouts (#6255)
+- Predicate cache in leaf search (#6024); skip CPU work when it cannot improve the result (#6001); propagate cancellation within leaf search (#6002)
+- Set `searcher.warmup_single_split_initial_allocation` default to 300 MB (#c34966c6)
+- Rebalance shards when ingester status changes (#6185) and improved rebalance algorithm (#6018)
+- Add object storage metrics for GCS (#5889)
+- Expose per-shard load configuration and disable the Tokio LIFO slot by default (#5898, #5899)
+- Redact sensitive information in developer API debug output (#6191)
 - Disable control plane check for searcher (#5599, #5360)
 - Partially implement `_elastic/_cluster/health` (#5595)
 - Make Jaeger span attribute-to-tag conversion exhaustive (#5574)
@@ -34,9 +64,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Limit and monitor warmup memory usage (#5568)
 - Add eviction metrics to caches (#5523)
 - Record object storage request latencies (#5521)
-- Add some kind of throttling on the janitor to prevent it from overloading (#5510)
+- Throttle the janitor to prevent overloading the metastore (#5510)
 - Prevent single split searches from different `leaf_search` from interleaving (#5509)
-- Retry on S3 internal error (#5504)
+- Retry on S3 internal error (#5504); make more S3 errors retryable (#5384)
 - Allow specifying OTEL index ID in header (#5503)
 - Add a metric to count storage errors and their error code (#5497)
 - Add support for concatenated fields (#4773, #5369, #5331)
@@ -47,14 +77,15 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Add some additional search metrics (#5447)
 - Improve GC resilience and add metrics (#5420)
 - Enable force shutdown with 2nd Ctrl+C (#5414)
-- Add request_timeout_secs config to searcher config (#5402)
+- Add `request_timeout_secs` to searcher config (#5402)
 - Memoize S3 client (#5377)
 - Add more env var config for Postgres (#5365)
 - Enable str fast field range queries (#5324)
 - Allow querying non-existing fields (#5308)
-- Support updating doc mapper through api (#5253)
 - Add optional special handling for hex in code tokenizer (#5200)
 - Added a circuit breaker layer (#5134)
+- Follow AWS hints for Lambda retries (#6195)
+- Improve cluster sizing documentation for control plane, metastore and janitor (#6202)
 - Various performance optimizations in Tantivy (https://github.com/quickwit-oss/tantivy/blob/main/CHANGELOG.md)
 
 ### Changed
@@ -68,10 +99,14 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Improve merge pipeline finalization (#5475)
 - Allow failed splits in root search (#5440)
 - Batch delete from GC (#5404, #5380)
-- Make some S3 errors retryable (#5384)
 - Change default timestamps in OTEL logs (#5366)
 - Only return root spans for Jaeger HTTP API (#5358)
 - Share aggregation limit on node (#5357)
+- Make regex lenient to start and end anchors (#6089) — *later reverted, see Fixed*
+- Use correct precision level for fastfield-based term queries on datetime (#6027)
+- Disable the Tokio LIFO slot and tune per-shard default load (#5898)
+- Improve control-plane logging (#6003)
+- Upgraded Tantivy to 9b61999 / 04beab3b29 with multiple search/aggregation perf improvements (see Tantivy CHANGELOG)
 
 ### Fixed
 - Fix existence queries for nested fields (#5581)
@@ -86,12 +121,30 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Fix configuration interpolation (#5403)
 - Fix jaeger duration parse error (#5518)
 - Fix unit conversion in jaeger http search endpoint (#5519)
+- Fix Kinesis source panic on resharding (#5912)
+- Fix Azure multipart upload data corruption (#5919)
+- Fix leaf list fields merging logic (#5908)
+- Fix empty intermediate aggregation results merge (#5930)
+- Fix error when running a scoring query with cache (#6025)
+- Fix `f64` not working properly with concatenated fields (#6074)
+- Fix wrong range result when datetime was inferred in JSON type (#6048)
+- Fix infinite-loop OOM bug caused by rebalancing shards from unavailable ingesters (#6078)
+- Fix index reincarnation routing bug (#6217)
+- Fix bug when deploying a new routing table (#6249)
+- Fix Chitchat gossip bug triggering excess gRPC traffic (#6082)
+- Revert over-eager anchor lenience in regex queries (#6089)
+- `skip_aggregation_finalization` fixes for composite aggregations
+- Jaeger: query resource attributes when the Jaeger request carries tags
 
 ### Removed
-- Remove support for 2-digit years in java datetime parser (#5596)
-- Remove DocMapper trait (#5508)
-- Remove support for AWS Lambda (#5884)
+- Remove support for 2-digit years in Java datetime parser (#5596)
+- Remove `DocMapper` trait (#5508)
+- Remove standalone AWS Lambda deployment mode — the previous dedicated search/indexing Lambda binaries are gone (#5884). *AWS Lambda is still supported for search offloading; see the Added section.*
 - Remove search stream endpoint (#5886)
+- Remove mentions of the stream API from the docs (#5958)
+- Remove the legacy `/api/v1/{index}/ingest-v2` REST endpoint (V2 is now served from `/ingest` — see Breaking / Migration)
+- Remove the unused multilang tokenizer feature (#6154)
+- Restrict stemming to the `multilang` feature (#6085)
 
 # [0.8.1]
 
diff --git a/docs/get-started/upgrade.md b/docs/get-started/upgrade.md
new file mode 100644
index 00000000000..8e0b797f29c
--- /dev/null
+++ b/docs/get-started/upgrade.md
@@ -0,0 +1,52 @@
+---
+title: Upgrade
+sidebar_position: 5
+---
+
+This page documents breaking changes and migration steps when upgrading Quickwit. If you are upgrading across multiple minor versions, apply the steps for each intermediate version in order.
+
+## Upgrading to 0.9
+
+1. **Back up your metastore.** If you use the PostgreSQL metastore, take a snapshot. If you use the file-backed metastore, keep a copy of the `indexes/` directory. 0.9 runs SQL migrations that add new columns (`maturity`, compaction-related fields) on first start; rolling back requires the backup.
+2. **Back up your index data (optional).** The on-disk split format and object-storage layout are unchanged, so no re-indexing is needed. A backup is still recommended if your storage is not already versioned.
+3. **Stop all 0.8.x nodes before starting any 0.9 node.** Mixed-version clusters are not supported during the migration.
+
+### Ingest V2
+
+In 0.8.x, ingest V2 was opt-in via `QW_ENABLE_INGEST_V2=true` and was served from a dedicated route `POST /api/v1/{index}/ingest-v2`.
+
+In 0.9:
+
+- `QW_ENABLE_INGEST_V2` now defaults to `true`.
+- `POST /api/v1/{index}/ingest` routes to V2 automatically. V1 still exists internally and can be reached per-request with `?use_legacy_ingest=true`, or cluster-wide by setting `QW_ENABLE_INGEST_V2=false`.
+- `POST /api/v1/{index}/ingest-v2` has been removed.
+- `QW_DISABLE_INGEST_V1=true` lets you force pure-V2 operation once all clients are migrated.
+
+**What changes operationally.** Ingest V2 shards commits across multiple indexers running in parallel. On a freshly-stopped ingest stream you may observe more (and smaller) splits than V1 produced, because the tail splits of each shard do not always meet the merge policy's `merge_factor` threshold. If you rely on a low steady-state split count, tune `indexing_settings.merge_policy.merge_factor` down (for example to `2`) in your index config or run the merge-on-demand path.
+
+### Configuration changes
+
+- **`rest_listen_port` is deprecated.** Move it under the new `rest` block:
+  ```yaml
+  # before (0.8.x, still works in 0.9 with a deprecation warning)
+  rest_listen_port: 7280
+
+  # after (0.9)
+  rest:
+    listen_port: 7280
+  ```
+  The old field keeps working for the 0.9 cycle to ease the transition; plan to remove it in 0.10.
+- **Stemming is now gated behind the `multilang` cargo feature.** If you build Quickwit from source and rely on stemming, add `--features multilang`. The official binaries and Docker images are built with `multilang` enabled, so users of the distributed images are unaffected.
+- The unused `multilang` *tokenizer* feature (distinct from the `multilang` cargo feature above) was removed. If you used a custom doc mapper referencing it, switch to the standard tokenizers.
+
+### Rust toolchain (for source builds only)
+
+Building from source now requires Rust **1.92** (tracked in `rust-toolchain.toml`). Users of the published Docker images or prebuilt binaries are unaffected.
+
+### Rolling back
+
+Rollback is one-way for the metastore. If you must return to 0.8.x, restore the metastore from the backup taken in step 1 of "Before you upgrade" and shut down all 0.9 nodes before starting any 0.8.x node.
+
+## Upgrading to earlier versions
+
+See the [CHANGELOG](https://github.com/quickwit-oss/quickwit/blob/main/CHANGELOG.md) for breaking changes in prior releases.
diff --git a/quickwit/Cargo.lock b/quickwit/Cargo.lock
index 2f169ffeae9..c4b16523eee 100644
--- a/quickwit/Cargo.lock
+++ b/quickwit/Cargo.lock
@@ -7042,7 +7042,7 @@ dependencies = [
 
 [[package]]
 name = "quickwit-actors"
-version = "0.8.0"
+version = "0.9.0"
 dependencies = [
  "anyhow",
  "async-trait",
@@ -7061,7 +7061,7 @@ dependencies = [
 
 [[package]]
 name = "quickwit-aws"
-version = "0.8.0"
+version = "0.9.0"
 dependencies = [
  "aws-config",
  "aws-runtime",
@@ -7076,7 +7076,7 @@ dependencies = [
 
 [[package]]
 name = "quickwit-cli"
-version = "0.8.0"
+version = "0.9.0"
 dependencies = [
  "anyhow",
  "backtrace",
@@ -7133,7 +7133,7 @@ dependencies = [
 
 [[package]]
 name = "quickwit-cluster"
-version = "0.8.0"
+version = "0.9.0"
 dependencies = [
  "anyhow",
  "async-trait",
@@ -7158,7 +7158,7 @@ dependencies = [
 
 [[package]]
 name = "quickwit-codegen"
-version = "0.8.0"
+version = "0.9.0"
 dependencies = [
  "anyhow",
  "futures",
@@ -7174,7 +7174,7 @@ dependencies = [
 
 [[package]]
 name = "quickwit-codegen-example"
-version = "0.8.0"
+version = "0.9.0"
 dependencies = [
  "anyhow",
  "async-trait",
@@ -7199,7 +7199,7 @@ dependencies = [
 
 [[package]]
 name = "quickwit-common"
-version = "0.8.0"
+version = "0.9.0"
 dependencies = [
  "anyhow",
  "async-speed-limit",
@@ -7243,7 +7243,7 @@ dependencies = [
 
 [[package]]
 name = "quickwit-config"
-version = "0.8.0"
+version = "0.9.0"
 dependencies = [
  "anyhow",
  "bytes",
@@ -7275,7 +7275,7 @@ dependencies = [
 
 [[package]]
 name = "quickwit-control-plane"
-version = "0.8.0"
+version = "0.9.0"
 dependencies = [
  "anyhow",
  "async-trait",
@@ -7305,7 +7305,7 @@ dependencies = [
 
 [[package]]
 name = "quickwit-datetime"
-version = "0.8.0"
+version = "0.9.0"
 dependencies = [
  "itertools 0.14.0",
  "serde",
@@ -7317,7 +7317,7 @@ dependencies = [
 
 [[package]]
 name = "quickwit-directories"
-version = "0.8.0"
+version = "0.9.0"
 dependencies = [
  "anyhow",
  "async-trait",
@@ -7334,7 +7334,7 @@ dependencies = [
 
 [[package]]
 name = "quickwit-doc-mapper"
-version = "0.8.0"
+version = "0.9.0"
 dependencies = [
  "anyhow",
  "base64 0.22.1",
@@ -7365,14 +7365,14 @@ dependencies = [
 
 [[package]]
 name = "quickwit-dst"
-version = "0.8.0"
+version = "0.9.0"
 dependencies = [
  "stateright",
 ]
 
 [[package]]
 name = "quickwit-index-management"
-version = "0.8.0"
+version = "0.9.0"
 dependencies = [
  "anyhow",
  "futures",
@@ -7392,7 +7392,7 @@ dependencies = [
 
 [[package]]
 name = "quickwit-indexing"
-version = "0.8.0"
+version = "0.9.0"
 dependencies = [
  "anyhow",
  "arc-swap",
@@ -7458,7 +7458,7 @@ dependencies = [
 
 [[package]]
 name = "quickwit-ingest"
-version = "0.8.0"
+version = "0.9.0"
 dependencies = [
  "anyhow",
  "async-trait",
@@ -7496,7 +7496,7 @@ dependencies = [
 
 [[package]]
 name = "quickwit-integration-tests"
-version = "0.8.0"
+version = "0.9.0"
 dependencies = [
  "anyhow",
  "aws-sdk-sqs",
@@ -7529,7 +7529,7 @@ dependencies = [
 
 [[package]]
 name = "quickwit-jaeger"
-version = "0.8.0"
+version = "0.9.0"
 dependencies = [
  "async-trait",
  "itertools 0.14.0",
@@ -7561,7 +7561,7 @@ dependencies = [
 
 [[package]]
 name = "quickwit-janitor"
-version = "0.8.0"
+version = "0.9.0"
 dependencies = [
  "anyhow",
  "async-trait",
@@ -7592,7 +7592,7 @@ dependencies = [
 
 [[package]]
 name = "quickwit-lambda-client"
-version = "0.8.0"
+version = "0.9.0"
 dependencies = [
  "anyhow",
  "async-trait",
@@ -7618,7 +7618,7 @@ dependencies = [
 
 [[package]]
 name = "quickwit-lambda-server"
-version = "0.8.0"
+version = "0.9.0"
 dependencies = [
  "anyhow",
  "base64 0.22.1",
@@ -7642,7 +7642,7 @@ dependencies = [
 
 [[package]]
 name = "quickwit-macros"
-version = "0.8.0"
+version = "0.9.0"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -7651,7 +7651,7 @@ dependencies = [
 
 [[package]]
 name = "quickwit-metastore"
-version = "0.8.0"
+version = "0.9.0"
 dependencies = [
  "anyhow",
  "async-trait",
@@ -7697,7 +7697,7 @@ dependencies = [
 
 [[package]]
 name = "quickwit-opentelemetry"
-version = "0.8.0"
+version = "0.9.0"
 dependencies = [
  "anyhow",
  "arrow",
@@ -7720,7 +7720,7 @@ dependencies = [
 
 [[package]]
 name = "quickwit-parquet-engine"
-version = "0.8.0"
+version = "0.9.0"
 dependencies = [
  "anyhow",
  "arrow",
@@ -7745,7 +7745,7 @@ dependencies = [
 
 [[package]]
 name = "quickwit-proto"
-version = "0.8.0"
+version = "0.9.0"
 dependencies = [
  "anyhow",
  "async-trait",
@@ -7784,7 +7784,7 @@ dependencies = [
 
 [[package]]
 name = "quickwit-query"
-version = "0.8.0"
+version = "0.9.0"
 dependencies = [
  "anyhow",
  "base64 0.22.1",
@@ -7809,7 +7809,7 @@ dependencies = [
 
 [[package]]
 name = "quickwit-rest-client"
-version = "0.8.0"
+version = "0.9.0"
 dependencies = [
  "anyhow",
  "bytes",
@@ -7835,7 +7835,7 @@ dependencies = [
 
 [[package]]
 name = "quickwit-search"
-version = "0.8.0"
+version = "0.9.0"
 dependencies = [
  "anyhow",
  "assert-json-diff",
@@ -7877,7 +7877,7 @@ dependencies = [
 
 [[package]]
 name = "quickwit-serve"
-version = "0.8.0"
+version = "0.9.0"
 dependencies = [
  "anyhow",
  "assert-json-diff",
@@ -7954,7 +7954,7 @@ dependencies = [
 
 [[package]]
 name = "quickwit-storage"
-version = "0.8.0"
+version = "0.9.0"
 dependencies = [
  "anyhow",
  "async-trait",
@@ -8004,7 +8004,7 @@ dependencies = [
 
 [[package]]
 name = "quickwit-telemetry"
-version = "0.8.0"
+version = "0.9.0"
 dependencies = [
  "async-trait",
  "encoding_rs",
diff --git a/quickwit/Cargo.toml b/quickwit/Cargo.toml
index 1211e0d598a..d4074a11a80 100644
--- a/quickwit/Cargo.toml
+++ b/quickwit/Cargo.toml
@@ -76,7 +76,7 @@ default-members = [
 ]
 
 [workspace.package]
-version = "0.8.0"
+version = "0.9.0"
 edition = "2024"
 homepage = "https://quickwit.io/"
 documentation = "https://quickwit.io/docs/"