diff --git a/app/vmagent/README.md b/app/vmagent/README.md
index 3b00d5153..c6ec547d9 100644
--- a/app/vmagent/README.md
+++ b/app/vmagent/README.md
@@ -358,6 +358,10 @@ It may be useful to perform `vmagent` rolling update without any scrape loss.
   Such gaps may appear because `vmagent` cannot keep up with sending the collected data to remote storage. Therefore it starts dropping the buffered data
   if the on-disk buffer size exceeds `-remoteWrite.maxDiskUsagePerURL`.
 
+* `vmagent` drops data blocks if remote storage replies with `400 Bad Request` and `409 Conflict` HTTP responses. The number of dropped blocks can be monitored via `vmagent_remotewrite_packets_dropped_total` metric exported at [/metrics page](#monitoring).
+
+* Use `-remoteWrite.queues=1` when `-remoteWrite.url` points to remote storage, which doesn't accept out-of-order samples (aka data backfilling). Such storage systems include Prometheus, Cortex and Thanos.
+
 * `vmagent` buffers scraped data at the `-remoteWrite.tmpDataPath` directory until it is sent to `-remoteWrite.url`.
   The directory can grow large when remote storage is unavailable for extended periods of time and if `-remoteWrite.maxDiskUsagePerURL` isn't set.
   If you don't want to send all the data from the directory to remote storage then simply stop `vmagent` and delete the directory.
diff --git a/docs/CHANGELOG.md b/docs/CHANGELOG.md
index aef0e210e..422f14000 100644
--- a/docs/CHANGELOG.md
+++ b/docs/CHANGELOG.md
@@ -17,6 +17,7 @@
 * BUGFIX: prevent from infinite loop in `/metrics/find` and `/metrics/expand` [Graphite Metrics API handlers](https://victoriametrics.github.io/#graphite-metrics-api-usage) when they match metric names or labels with `*`, `{` or `[` chars.
 * BUGFIX: do not merge duplicate time series during requests to `/api/v1/query`. See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1141
 * BUGFIX: vmagent: properly handle `too old resource version` error messages from Kubernetes watch API. See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1150
+* BUGFIX: vmagent: do not retry sending data blocks if remote storage returns `400 Bad Request` error. The number of dropped blocks due to such errors can be monitored with `vmagent_remotewrite_packets_dropped_total` metrics. See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1149
 
 
 # [v1.56.0](https://github.com/VictoriaMetrics/VictoriaMetrics/releases/tag/v1.56.0)
diff --git a/docs/vmagent.md b/docs/vmagent.md
index 3b00d5153..c6ec547d9 100644
--- a/docs/vmagent.md
+++ b/docs/vmagent.md
@@ -358,6 +358,10 @@ It may be useful to perform `vmagent` rolling update without any scrape loss.
   Such gaps may appear because `vmagent` cannot keep up with sending the collected data to remote storage. Therefore it starts dropping the buffered data
   if the on-disk buffer size exceeds `-remoteWrite.maxDiskUsagePerURL`.
 
+* `vmagent` drops data blocks if remote storage replies with `400 Bad Request` and `409 Conflict` HTTP responses. The number of dropped blocks can be monitored via `vmagent_remotewrite_packets_dropped_total` metric exported at [/metrics page](#monitoring).
+
+* Use `-remoteWrite.queues=1` when `-remoteWrite.url` points to remote storage, which doesn't accept out-of-order samples (aka data backfilling). Such storage systems include Prometheus, Cortex and Thanos.
+
 * `vmagent` buffers scraped data at the `-remoteWrite.tmpDataPath` directory until it is sent to `-remoteWrite.url`.
   The directory can grow large when remote storage is unavailable for extended periods of time and if `-remoteWrite.maxDiskUsagePerURL` isn't set.
   If you don't want to send all the data from the directory to remote storage then simply stop `vmagent` and delete the directory.