diff --git a/x-pack/platform/plugins/shared/alerting/server/alerts_service/alerts_service.test.ts b/x-pack/platform/plugins/shared/alerting/server/alerts_service/alerts_service.test.ts
index 979acd67a2d73..77f01b32d5c01 100644
--- a/x-pack/platform/plugins/shared/alerting/server/alerts_service/alerts_service.test.ts
+++ b/x-pack/platform/plugins/shared/alerting/server/alerts_service/alerts_service.test.ts
@@ -473,14 +473,12 @@ describe('Alerts Service', () => {
           expect(clusterClient.indices.putIndexTemplate).toHaveBeenCalledTimes(1);
           expect(clusterClient.indices.putIndexTemplate).toHaveBeenCalledWith({
             name: existingIndexTemplate.name,
-            body: {
-              ...existingIndexTemplate.index_template,
-              template: {
-                ...existingIndexTemplate.index_template.template,
-                settings: {
-                  ...existingIndexTemplate.index_template.template?.settings,
-                  'index.mapping.total_fields.limit': 2500,
-                },
+            ...existingIndexTemplate.index_template,
+            template: {
+              ...existingIndexTemplate.index_template.template,
+              settings: {
+                ...existingIndexTemplate.index_template.template?.settings,
+                'index.mapping.total_fields.limit': 2500,
               },
             },
           });
diff --git a/x-pack/platform/plugins/shared/alerting/server/alerts_service/lib/create_concrete_write_index.ts b/x-pack/platform/plugins/shared/alerting/server/alerts_service/lib/create_concrete_write_index.ts
index 84fe76d71aca2..8ecd2cfc89aca 100644
--- a/x-pack/platform/plugins/shared/alerting/server/alerts_service/lib/create_concrete_write_index.ts
+++ b/x-pack/platform/plugins/shared/alerting/server/alerts_service/lib/create_concrete_write_index.ts
@@ -90,8 +90,7 @@ const updateUnderlyingMapping = async ({
 
   try {
     await retryTransientEsErrors(
-      // @ts-expect-error elasticsearch@9.0.0 https://github.com/elastic/elasticsearch-js/issues/2584
-      () => esClient.indices.putMapping({ index, body: simulatedMapping }),
+      () => esClient.indices.putMapping({ index, ...simulatedMapping }),
       { logger }
     );
 
diff --git a/x-pack/platform/plugins/shared/alerting/server/alerts_service/lib/create_or_update_component_template.test.ts b/x-pack/platform/plugins/shared/alerting/server/alerts_service/lib/create_or_update_component_template.test.ts
index 0f53d1eadb976..ab7b13c822083 100644
--- a/x-pack/platform/plugins/shared/alerting/server/alerts_service/lib/create_or_update_component_template.test.ts
+++ b/x-pack/platform/plugins/shared/alerting/server/alerts_service/lib/create_or_update_component_template.test.ts
@@ -177,14 +177,12 @@ describe('createOrUpdateComponentTemplate', () => {
     expect(clusterClient.indices.putIndexTemplate).toHaveBeenCalledTimes(1);
     expect(clusterClient.indices.putIndexTemplate).toHaveBeenCalledWith({
       name: existingIndexTemplate.name,
-      body: {
-        ...existingIndexTemplate.index_template,
-        template: {
-          ...existingIndexTemplate.index_template.template,
-          settings: {
-            ...existingIndexTemplate.index_template.template?.settings,
-            'index.mapping.total_fields.limit': 2500,
-          },
+      ...existingIndexTemplate.index_template,
+      template: {
+        ...existingIndexTemplate.index_template.template,
+        settings: {
+          ...existingIndexTemplate.index_template.template?.settings,
+          'index.mapping.total_fields.limit': 2500,
         },
       },
     });
@@ -283,14 +281,12 @@ describe('createOrUpdateComponentTemplate', () => {
     expect(clusterClient.indices.putIndexTemplate).toHaveBeenCalledTimes(1);
     expect(clusterClient.indices.putIndexTemplate).toHaveBeenCalledWith({
       name: existingIndexTemplate.name,
-      body: {
-        ...existingIndexTemplate.index_template,
-        template: {
-          ...existingIndexTemplate.index_template.template,
-          settings: {
-            ...existingIndexTemplate.index_template.template?.settings,
-            'index.mapping.total_fields.limit': 2500,
-          },
+      ...existingIndexTemplate.index_template,
+      template: {
+        ...existingIndexTemplate.index_template.template,
+        settings: {
+          ...existingIndexTemplate.index_template.template?.settings,
+          'index.mapping.total_fields.limit': 2500,
         },
       },
     });
diff --git a/x-pack/platform/plugins/shared/alerting/server/alerts_service/lib/create_or_update_component_template.ts b/x-pack/platform/plugins/shared/alerting/server/alerts_service/lib/create_or_update_component_template.ts
index 778795fd46eca..06675a1998bc8 100644
--- a/x-pack/platform/plugins/shared/alerting/server/alerts_service/lib/create_or_update_component_template.ts
+++ b/x-pack/platform/plugins/shared/alerting/server/alerts_service/lib/create_or_update_component_template.ts
@@ -50,17 +50,19 @@ const getIndexTemplatesUsingComponentTemplate = async (
         () =>
           esClient.indices.putIndexTemplate({
             name: template.name,
-            body: {
-              ...template.index_template,
-              // @ts-expect-error elasticsearch@9.0.0 https://github.com/elastic/elasticsearch-js/issues/2584
-              template: {
-                ...template.index_template.template,
-                settings: {
-                  ...template.index_template.template?.settings,
-                  'index.mapping.total_fields.limit': totalFieldsLimit,
-                },
+            ...template.index_template,
+            template: {
+              ...template.index_template.template,
+              settings: {
+                ...template.index_template.template?.settings,
+                'index.mapping.total_fields.limit': totalFieldsLimit,
               },
             },
+            // GET brings string | string[] | undefined but this PUT expects string[]
+            ignore_missing_component_templates: template.index_template
+              .ignore_missing_component_templates
+              ? [template.index_template.ignore_missing_component_templates].flat()
+              : undefined,
           }),
         { logger }
       );
diff --git a/x-pack/platform/plugins/shared/event_log/server/es/cluster_client_adapter.test.ts b/x-pack/platform/plugins/shared/event_log/server/es/cluster_client_adapter.test.ts
index bdf72d753485a..c8695efc53a24 100644
--- a/x-pack/platform/plugins/shared/event_log/server/es/cluster_client_adapter.test.ts
+++ b/x-pack/platform/plugins/shared/event_log/server/es/cluster_client_adapter.test.ts
@@ -379,13 +379,11 @@ describe('setLegacyIndexTemplateToHidden', () => {
     await clusterClientAdapter.setLegacyIndexTemplateToHidden('foo-bar-template', currentTemplate);
     expect(clusterClient.indices.putTemplate).toHaveBeenCalledWith({
       name: 'foo-bar-template',
-      body: {
-        order: 0,
-        index_patterns: ['foo-bar-*'],
-        settings: { index: { number_of_shards: '1' }, 'index.hidden': true },
-        mappings: { dynamic: false, properties: {} },
-        aliases: {},
-      },
+      order: 0,
+      index_patterns: ['foo-bar-*'],
+      settings: { index: { number_of_shards: '1' }, 'index.hidden': true },
+      mappings: { dynamic: false, properties: {} },
+      aliases: {},
     });
   });
 
@@ -659,7 +657,8 @@ describe('updateConcreteIndices', () => {
     });
     expect(clusterClient.indices.putMapping).toHaveBeenCalledWith({
       index: 'foo',
-      body: { dynamic: false, properties: { '@timestamp': { type: 'date' } } },
+      dynamic: false,
+      properties: { '@timestamp': { type: 'date' } },
     });
   });
 
@@ -720,7 +719,8 @@ describe('updateConcreteIndices', () => {
 
     expect(clusterClient.indices.putMapping).toHaveBeenCalledWith({
       index: 'foo',
-      body: { dynamic: false, properties: { '@timestamp': { type: 'date' } } },
+      dynamic: false,
+      properties: { '@timestamp': { type: 'date' } },
     });
     expect(logger.error).toHaveBeenCalledWith(
       `Error updating index mappings for foo: failed to put mappings`
diff --git a/x-pack/platform/plugins/shared/event_log/server/es/cluster_client_adapter.ts b/x-pack/platform/plugins/shared/event_log/server/es/cluster_client_adapter.ts
index 9f2a0809ee8f5..a9b895544e2a2 100644
--- a/x-pack/platform/plugins/shared/event_log/server/es/cluster_client_adapter.ts
+++ b/x-pack/platform/plugins/shared/event_log/server/es/cluster_client_adapter.ts
@@ -339,13 +339,10 @@ export class ClusterClientAdapter<
       const esClient = await this.elasticsearchClientPromise;
       await esClient.indices.putTemplate({
         name: indexTemplateName,
-        body: {
-          ...currentIndexTemplate,
-          // @ts-expect-error elasticsearch@9.0.0 https://github.com/elastic/elasticsearch-js/issues/2584
-          settings: {
-            ...currentIndexTemplate.settings,
-            'index.hidden': true,
-          },
+        ...currentIndexTemplate,
+        settings: {
+          ...currentIndexTemplate.settings,
+          'index.hidden': true,
         },
       });
     } catch (err) {
@@ -461,8 +458,7 @@ export class ClusterClientAdapter<
       const simulatedMapping = get(simulatedIndexMapping, ['template', 'mappings']);
 
       if (simulatedMapping != null) {
-        // @ts-expect-error elasticsearch@9.0.0 https://github.com/elastic/elasticsearch-js/issues/2584
-        await esClient.indices.putMapping({ index: name, body: simulatedMapping });
+        await esClient.indices.putMapping({ index: name, ...simulatedMapping });
         this.logger.debug(`Successfully updated concrete index mappings for ${name}`);
       }
     } catch (err) {
diff --git a/x-pack/platform/plugins/shared/task_manager/server/task_store.ts b/x-pack/platform/plugins/shared/task_manager/server/task_store.ts
index 67fe82086daa6..d0e0b3776ba04 100644
--- a/x-pack/platform/plugins/shared/task_manager/server/task_store.ts
+++ b/x-pack/platform/plugins/shared/task_manager/server/task_store.ts
@@ -902,24 +902,24 @@ export class TaskStore {
     { max_docs: max_docs }: UpdateByQueryOpts = {}
   ): Promise<UpdateByQueryResult> {
     const { query } = ensureQueryOnlyReturnsTaskObjects(opts);
+    const { sort, ...rest } = opts;
     try {
-      const // @ts-expect-error elasticsearch@9.0.0 https://github.com/elastic/elasticsearch-js/issues/2584 types complain because the body should not be there.
-        // However, we can't use this API without the body because it fails to claim the tasks.
-        // eslint-disable-next-line @typescript-eslint/naming-convention
-        { total, updated, version_conflicts } = await this.esClientWithoutRetries.updateByQuery(
-          {
-            index: this.index,
-            ignore_unavailable: true,
-            refresh: true,
-            conflicts: 'proceed',
-            body: {
-              ...opts,
-              max_docs,
-              query,
-            },
-          },
-          { requestTimeout: this.requestTimeouts.update_by_query }
-        );
+      // eslint-disable-next-line @typescript-eslint/naming-convention
+      const { total, updated, version_conflicts } = await this.esClientWithoutRetries.updateByQuery(
+        {
+          index: this.index,
+          ignore_unavailable: true,
+          refresh: true,
+          conflicts: 'proceed',
+          ...rest,
+          max_docs,
+          query,
+          // @ts-expect-error According to the docs, sort should be a comma-separated list of fields and goes in the querystring.
+          // However, this one is using a "body" format?
+          body: { sort },
+        },
+        { requestTimeout: this.requestTimeouts.update_by_query }
+      );
 
       const conflictsCorrectedForContinuation = correctVersionConflictsForContinuation(
         updated,