diff --git a/x-pack/plugins/fleet/server/errors/index.ts b/x-pack/plugins/fleet/server/errors/index.ts
index 700750761def4..6e25a4719cd0f 100644
--- a/x-pack/plugins/fleet/server/errors/index.ts
+++ b/x-pack/plugins/fleet/server/errors/index.ts
@@ -31,3 +31,5 @@ export class PackageCacheError extends IngestManagerError {}
 export class PackageOperationNotSupportedError extends IngestManagerError {}
 export class FleetAdminUserInvalidError extends IngestManagerError {}
 export class ConcurrentInstallOperationError extends IngestManagerError {}
+export class AgentReassignmentError extends IngestManagerError {}
+export class AgentUnenrollmentError extends IngestManagerError {}
diff --git a/x-pack/plugins/fleet/server/services/agents/reassign.test.ts b/x-pack/plugins/fleet/server/services/agents/reassign.test.ts
index 49a38166e9cc7..5a940818c280d 100644
--- a/x-pack/plugins/fleet/server/services/agents/reassign.test.ts
+++ b/x-pack/plugins/fleet/server/services/agents/reassign.test.ts
@@ -7,6 +7,7 @@
 import { elasticsearchServiceMock, savedObjectsClientMock } from 'src/core/server/mocks';
 import type { SavedObject } from 'kibana/server';
 import type { Agent, AgentPolicy } from '../../types';
+import { AgentReassignmentError } from '../../errors';
 import { reassignAgent, reassignAgents } from './reassign';
 
 const agentInManagedSO = {
@@ -57,7 +58,7 @@ describe('reassignAgent (singular)', () => {
         agentInUnmanagedSO.id,
         agentInManagedSO.attributes.policy_id!
       )
-    ).rejects.toThrow('to managed');
+    ).rejects.toThrowError(AgentReassignmentError);
 
     // does not call ES update
     expect(soClient.update).toBeCalledTimes(0);
@@ -68,13 +69,13 @@ describe('reassignAgent (singular)', () => {
     const esClient = elasticsearchServiceMock.createClusterClient().asInternalUser;
     await expect(
       reassignAgent(soClient, esClient, agentInManagedSO.id, agentInManagedSO2.id)
-    ).rejects.toThrow('from managed');
+    ).rejects.toThrowError(AgentReassignmentError);
     // does not call ES update
     expect(soClient.update).toBeCalledTimes(0);
 
     await expect(
       reassignAgent(soClient, esClient, agentInManagedSO.id, agentInUnmanagedSO.id)
-    ).rejects.toThrow('from managed');
+    ).rejects.toThrowError(AgentReassignmentError);
     // does not call ES update
     expect(soClient.update).toBeCalledTimes(0);
   });
diff --git a/x-pack/plugins/fleet/server/services/agents/reassign.ts b/x-pack/plugins/fleet/server/services/agents/reassign.ts
index c29ace6e6245b..97ab737734734 100644
--- a/x-pack/plugins/fleet/server/services/agents/reassign.ts
+++ b/x-pack/plugins/fleet/server/services/agents/reassign.ts
@@ -4,10 +4,11 @@
  * you may not use this file except in compliance with the Elastic License.
  */
 
-import { SavedObjectsClientContract, ElasticsearchClient } from 'kibana/server';
+import type { SavedObjectsClientContract, ElasticsearchClient } from 'kibana/server';
 import Boom from '@hapi/boom';
 import { AGENT_SAVED_OBJECT_TYPE } from '../../constants';
-import { AgentSOAttributes } from '../../types';
+import type { AgentSOAttributes } from '../../types';
+import { AgentReassignmentError } from '../../errors';
 import { agentPolicyService } from '../agent_policy';
 import { getAgentPolicyForAgent, getAgents, listAllAgents } from './crud';
 import { createAgentAction, bulkCreateAgentActions } from './actions';
@@ -45,12 +46,16 @@ export async function reassignAgentIsAllowed(
 ) {
   const agentPolicy = await getAgentPolicyForAgent(soClient, esClient, agentId);
   if (agentPolicy?.is_managed) {
-    throw new Error(`Cannot reassign an agent from managed agent policy ${agentPolicy.id}`);
+    throw new AgentReassignmentError(
+      `Cannot reassign an agent from managed agent policy ${agentPolicy.id}`
+    );
   }
 
   const newAgentPolicy = await agentPolicyService.get(soClient, newAgentPolicyId);
   if (newAgentPolicy?.is_managed) {
-    throw new Error(`Cannot reassign an agent to managed agent policy ${newAgentPolicy.id}`);
+    throw new AgentReassignmentError(
+      `Cannot reassign an agent to managed agent policy ${newAgentPolicy.id}`
+    );
   }
 
   return true;
diff --git a/x-pack/plugins/fleet/server/services/agents/unenroll.test.ts b/x-pack/plugins/fleet/server/services/agents/unenroll.test.ts
index 57ac6d4334885..a65d64d0e8ae1 100644
--- a/x-pack/plugins/fleet/server/services/agents/unenroll.test.ts
+++ b/x-pack/plugins/fleet/server/services/agents/unenroll.test.ts
@@ -7,6 +7,7 @@
 import { elasticsearchServiceMock, savedObjectsClientMock } from 'src/core/server/mocks';
 import type { SavedObject } from 'kibana/server';
 import type { Agent, AgentPolicy } from '../../types';
+import { AgentUnenrollmentError } from '../../errors';
 import { unenrollAgent, unenrollAgents } from './unenroll';
 
 const agentInManagedSO = {
@@ -46,7 +47,9 @@ describe('unenrollAgent (singular)', () => {
   it('cannot unenroll from managed policy', async () => {
     const soClient = createClientMock();
     const esClient = elasticsearchServiceMock.createClusterClient().asInternalUser;
-    await expect(unenrollAgent(soClient, esClient, agentInManagedSO.id)).rejects.toThrow('managed');
+    await expect(unenrollAgent(soClient, esClient, agentInManagedSO.id)).rejects.toThrowError(
+      AgentUnenrollmentError
+    );
     // does not call ES update
     expect(soClient.update).toBeCalledTimes(0);
   });
diff --git a/x-pack/plugins/fleet/server/services/agents/unenroll.ts b/x-pack/plugins/fleet/server/services/agents/unenroll.ts
index eab99d9cc145d..aec628e78e405 100644
--- a/x-pack/plugins/fleet/server/services/agents/unenroll.ts
+++ b/x-pack/plugins/fleet/server/services/agents/unenroll.ts
@@ -3,8 +3,9 @@
  * or more contributor license agreements. Licensed under the Elastic License;
  * you may not use this file except in compliance with the Elastic License.
  */
-import { ElasticsearchClient, SavedObjectsClientContract } from 'src/core/server';
-import { AgentSOAttributes } from '../../types';
+import type { ElasticsearchClient, SavedObjectsClientContract } from 'src/core/server';
+import type { AgentSOAttributes } from '../../types';
+import { AgentUnenrollmentError } from '../../errors';
 import { AGENT_SAVED_OBJECT_TYPE } from '../../constants';
 import * as APIKeyService from '../api_keys';
 import { createAgentAction, bulkCreateAgentActions } from './actions';
@@ -17,7 +18,9 @@ async function unenrollAgentIsAllowed(
 ) {
   const agentPolicy = await getAgentPolicyForAgent(soClient, esClient, agentId);
   if (agentPolicy?.is_managed) {
-    throw new Error(`Cannot unenroll ${agentId} from a managed agent policy ${agentPolicy.id}`);
+    throw new AgentUnenrollmentError(
+      `Cannot unenroll ${agentId} from a managed agent policy ${agentPolicy.id}`
+    );
   }
 
   return true;
diff --git a/x-pack/test/fleet_api_integration/apis/agents/reassign.ts b/x-pack/test/fleet_api_integration/apis/agents/reassign.ts
index ae0da2eb759f6..d0e6ca2f8e8b6 100644
--- a/x-pack/test/fleet_api_integration/apis/agents/reassign.ts
+++ b/x-pack/test/fleet_api_integration/apis/agents/reassign.ts
@@ -14,10 +14,10 @@ export default function (providerContext: FtrProviderContext) {
 
   describe('fleet_reassign_agent', () => {
     setupFleetAndAgents(providerContext);
-    before(async () => {
+    beforeEach(async () => {
       await esArchiver.loadIfNeeded('fleet/agents');
     });
-    after(async () => {
+    afterEach(async () => {
       await esArchiver.unload('fleet/agents');
     });
 
@@ -86,5 +86,34 @@ export default function (providerContext: FtrProviderContext) {
         })
         .expect(404);
     });
+
+    it('can reassign from unmanaged policy to unmanaged', async () => {
+      // policy2 is not managed
+      // reassign succeeds
+      await supertest
+        .put(`/api/fleet/agents/agent1/reassign`)
+        .set('kbn-xsrf', 'xxx')
+        .send({
+          policy_id: 'policy2',
+        })
+        .expect(200);
+    });
+    it('cannot reassign from unmanaged policy to managed', async () => {
+      // agent1 is enrolled in policy1. set policy1 to managed
+      await supertest
+        .put(`/api/fleet/agent_policies/policy1`)
+        .set('kbn-xsrf', 'xxx')
+        .send({ name: 'Test policy', namespace: 'default', is_managed: true })
+        .expect(200);
+
+      // reassign fails
+      await supertest
+        .put(`/api/fleet/agents/agent1/reassign`)
+        .set('kbn-xsrf', 'xxx')
+        .send({
+          policy_id: 'policy2',
+        })
+        .expect(400);
+    });
   });
 }
diff --git a/x-pack/test/fleet_api_integration/apis/agents/unenroll.ts b/x-pack/test/fleet_api_integration/apis/agents/unenroll.ts
index 6192ecddea9ef..87dc636b180e9 100644
--- a/x-pack/test/fleet_api_integration/apis/agents/unenroll.ts
+++ b/x-pack/test/fleet_api_integration/apis/agents/unenroll.ts
@@ -72,7 +72,7 @@ export default function (providerContext: FtrProviderContext) {
         .send({ name: 'Test policy', namespace: 'default', is_managed: true })
         .expect(200);
 
-      await supertest.post(`/api/fleet/agents/agent1/unenroll`).set('kbn-xsrf', 'xxx').expect(500);
+      await supertest.post(`/api/fleet/agents/agent1/unenroll`).set('kbn-xsrf', 'xxx').expect(400);
     });
 
     it('/agents/{agent_id}/unenroll should allow from unmanaged policy', async () => {