doc: Updatesmongodbatlas_advanced_cluster ISS migration guide & resource doc with expected 500 error on update (#2525)

Author: maastha

.changelog/2478.txt

@@ -3,7 +3,7 @@ resource/mongodbatlas_advanced_cluster: Supports defining cluster shards with in
 ```
 
 ```release-note:note
-resource/mongodbatlas_advanced_cluster: Using this new version impacts the possibility of editing the definition of multi shard clusters in the Atlas UI. This impact is limited to the first weeks of August.
+resource/mongodbatlas_advanced_cluster: Using this new version impacts the possibility of editing the definition of multi shard clusters in the Atlas UI. This impact is limited to the first weeks of September.
 ```
 
 ```release-note:enhancement

CHANGELOG.md

@@ -22,7 +22,7 @@ NOTES:
 * data-source/mongodbatlas_advanced_cluster: Deprecates `replication_specs.#.id`, `replication_specs.#.num_shards`, `disk_size_gb`, `advanced_configuration.0.default_read_concern`, and  `advanced_configuration.0.fail_index_key_too_long`. To learn more, see the [1.18.0 Migration Guide](https://registry.terraform.io/providers/mongodb/mongodbatlas/latest/docs/guides/1.18.0-upgrade-guide). ([#2420](https://github.com/mongodb/terraform-provider-mongodbatlas/pull/2420))
 * data-source/mongodbatlas_advanced_clusters: Deprecates `replication_specs.#.id`, `replication_specs.#.num_shards`, `disk_size_gb`, `advanced_configuration.0.default_read_concern`, and  `advanced_configuration.0.fail_index_key_too_long`. To learn more, see the [1.18.0 Migration Guide](https://registry.terraform.io/providers/mongodb/mongodbatlas/latest/docs/guides/1.18.0-upgrade-guide). ([#2420](https://github.com/mongodb/terraform-provider-mongodbatlas/pull/2420))
 * resource/mongodbatlas_advanced_cluster: Deprecates `replication_specs.#.id`, `replication_specs.#.num_shards`, `disk_size_gb`, `advanced_configuration.0.default_read_concern`, and  `advanced_configuration.0.fail_index_key_too_long`. To learn more, see the [1.18.0 Migration Guide](https://registry.terraform.io/providers/mongodb/mongodbatlas/latest/docs/guides/1.18.0-upgrade-guide). ([#2420](https://github.com/mongodb/terraform-provider-mongodbatlas/pull/2420))
-* resource/mongodbatlas_advanced_cluster: Using this new version impacts the possibility of editing the definition of multi shard clusters in the Atlas UI. This impact is limited to the first weeks of August. ([#2478](https://github.com/mongodb/terraform-provider-mongodbatlas/pull/2478))
+* resource/mongodbatlas_advanced_cluster: Using this new version impacts the possibility of editing the definition of multi shard clusters in the Atlas UI. This impact is limited to the first weeks of September. ([#2478](https://github.com/mongodb/terraform-provider-mongodbatlas/pull/2478))
 
 FEATURES:
 

docs/guides/1.18.0-upgrade-guide.md

@@ -4,7 +4,7 @@ page_title: "Upgrade Guide 1.18.0"
 
 # MongoDB Atlas Provider 1.18.0: Upgrade and Information Guide
 
-***WARNING:*** For users using the `mongodbatlas_advanced_cluster` resource or data sources, and defining multi sharded clusters, this new version impacts the possibility of editing the definition of these clusters from the Atlas UI. This impact is limited to the first weeks of August 2024.
+***WARNING:*** For users using the `mongodbatlas_advanced_cluster` resource or data sources, and defining multi sharded clusters, this new version impacts the possibility of editing the definition of these clusters from the Atlas UI. This impact is limited to the first weeks of September 2024.
 
 The Terraform MongoDB Atlas Provider version 1.18.0 has a number of new and exciting features.
 

docs/guides/advanced-cluster-new-sharding-schema.md

@@ -84,6 +84,8 @@ resource "mongodbatlas_advanced_cluster" "test" {
 
 This updated configuration will trigger a Terraform update plan. However, the underlying cluster will not face any changes after the `apply` command, as both configurations represent a sharded cluster composed of two shards.
 
+Note: The first time `terraform apply` command is run **after** updating the configuration, you may receive a `500 Internal Server Error (Error code: "SERVICE_UNAVAILABLE")` error. This is a known temporary issue. If you encounter this, please re-run `terraform apply` and this time the update should succeed. 
+
 <a id="migration-geosharded"></a>
 ### Migrate advanced_cluster type `GEOSHARDED`
 
@@ -192,6 +194,8 @@ resource "mongodbatlas_advanced_cluster" "test" {
 
 This updated configuration triggers a Terraform update plan. However, the underlying cluster will not face any changes after the `apply` command, as both configurations represent a geo sharded cluster with two zones and two shards in each one.
 
+Note: The first time `terraform apply` command is run **after** updating the configuration, you may receive a `500 Internal Server Error (Error code: "SERVICE_UNAVAILABLE")` error. This is a known temporary issue. If you encounter this, please re-run `terraform apply` and this time the update should succeed. 
+
 <a id="migration-replicaset"></a>
 ### Migrate advanced_cluster type `REPLICASET`
 
@@ -274,6 +278,8 @@ resource "mongodbatlas_advanced_cluster" "test" {
 }
 ```
 
+Note: The first time `terraform apply` command is run **after** updating the configuration, you may receive a `500 Internal Server Error (Error code: "SERVICE_UNAVAILABLE")` error. This is a known temporary issue. If you encounter this, please re-run `terraform apply` and this time the update should succeed. 
+
 <a id="use-iss"></a>
 ### Use Independent Shard Scaling 
 

docs/resources/advanced_cluster.md

@@ -693,3 +693,4 @@ See detailed information for arguments and attributes: [MongoDB API Advanced Clu
 
 ~> **IMPORTANT:**
 <br> &#8226; When a cluster is imported, the resulting schema structure will always return the new schema including `replication_specs` per independent shards of the cluster.
+<br> &#8226;  Note: The first time `terraform apply` command is run **after** updating the configuration of an imported cluster, you may receive a `500 Internal Server Error (Error code: "SERVICE_UNAVAILABLE")` error. This is a known temporary issue. If you encounter this, please re-run `terraform apply` and this time the update should succeed.