diff --git a/codegen/lib/layouts/resources.ts b/codegen/lib/layouts/resources.ts
index 718edb96..4d05e5c7 100644
--- a/codegen/lib/layouts/resources.ts
+++ b/codegen/lib/layouts/resources.ts
@@ -1,4 +1,9 @@
-import type { Blueprint, Resource } from '@seamapi/blueprint'
+import type {
+  ActionAttempt,
+  Blueprint,
+  Property,
+  Resource,
+} from '@seamapi/blueprint'
 import { kebabCase, pascalCase } from 'change-case'
 
 export interface ResourceLayoutContext {
@@ -39,7 +44,7 @@ export const getResourceLayoutContexts = (
       ({ resourceType }) => !discriminatedResourceTypes.has(resourceType),
     ),
     ...blueprint.events,
-    ...blueprint.actionAttempts,
+    ...blueprint.actionAttempts.map(normalizeActionAttempt),
   ]
   const resourceTypes = [
     ...new Set(resources.map(({ resourceType }) => resourceType)),
@@ -57,6 +62,27 @@ export const getResourceLayoutContexts = (
   }))
 }
 
+// The blueprint merges the per-status variants and drops the nullability.
+const nullWhilePendingDoc =
+  'Null while the action attempt is pending or when this value does not apply.'
+
+const normalizeActionAttempt = (resource: ActionAttempt): ActionAttempt => ({
+  ...resource,
+  properties: resource.properties.map((property) =>
+    property.name === 'error' || property.name === 'result'
+      ? toStatusDependentProperty(property)
+      : property,
+  ),
+})
+
+const toStatusDependentProperty = (property: Property): Property => ({
+  ...property,
+  isNullable: true,
+  description: [property.description, nullWhilePendingDoc]
+    .filter((part) => part !== '')
+    .join(' '),
+})
+
 const getBatchResourceLayoutContexts = (
   resources: Resource[],
 ): BatchResourceLayoutContext[] => {
diff --git a/src/lib/resolve-action-attempt.ts b/src/lib/resolve-action-attempt.ts
index 5e137011..e55639d8 100644
--- a/src/lib/resolve-action-attempt.ts
+++ b/src/lib/resolve-action-attempt.ts
@@ -120,9 +120,10 @@ export class SeamActionAttemptFailedError<
   code: string
 
   constructor(actionAttempt: FailedActionAttempt<T>) {
-    super(actionAttempt.error.message, actionAttempt)
+    const { error } = actionAttempt as T
+    super(error?.message ?? 'Action attempt failed', actionAttempt)
     this.name = this.constructor.name
-    this.code = actionAttempt.error.type
+    this.code = error?.type ?? 'unknown'
   }
 }
 
@@ -164,6 +165,8 @@ const isFailedActionAttempt = <T extends ActionAttempt>(
  */
 export type SucceededActionAttempt<T extends ActionAttempt> = T & {
   status: 'success'
+  result: NonNullable<T['result']>
+  error: null
 }
 
 /**
@@ -171,4 +174,6 @@ export type SucceededActionAttempt<T extends ActionAttempt> = T & {
  */
 export type FailedActionAttempt<T extends ActionAttempt> = T & {
   status: 'error'
+  error: NonNullable<T['error']>
+  result: null
 }
diff --git a/src/lib/resources/action-attempt.ts b/src/lib/resources/action-attempt.ts
index 2b6d7cd5..cdcc58a4 100644
--- a/src/lib/resources/action-attempt.ts
+++ b/src/lib/resources/action-attempt.ts
@@ -19,7 +19,7 @@ export type ActionAttempt =
       action_type: 'LOCK_DOOR'
 
       /**
-       * Error associated with the action.
+       * Error associated with the action. Null while the action attempt is pending or when this value does not apply.
        */
       error: {
         /**
@@ -31,17 +31,16 @@ export type ActionAttempt =
          * Type of the error.
          */
         type: string
-      }
-
+      } | null
       /**
-       * Result of the action.
+       * Result of the action. Null while the action attempt is pending or when this value does not apply.
        */
       result: {
         /**
          * Indicates whether the device confirmed that the lock action occurred.
          */
         was_confirmed_by_device?: boolean | undefined
-      }
+      } | null
 
       status: 'success' | 'pending' | 'error'
     }
@@ -57,7 +56,7 @@ export type ActionAttempt =
       action_type: 'UNLOCK_DOOR'
 
       /**
-       * Error associated with the action.
+       * Error associated with the action. Null while the action attempt is pending or when this value does not apply.
        */
       error: {
         /**
@@ -69,17 +68,16 @@ export type ActionAttempt =
          * Type of the error.
          */
         type: string
-      }
-
+      } | null
       /**
-       * Result of the action.
+       * Result of the action. Null while the action attempt is pending or when this value does not apply.
        */
       result: {
         /**
          * Indicates whether the device confirmed that the unlock action occurred.
          */
         was_confirmed_by_device?: boolean | undefined
-      }
+      } | null
 
       status: 'success' | 'pending' | 'error'
     }
@@ -94,6 +92,9 @@ export type ActionAttempt =
        */
       action_type: 'SCAN_CREDENTIAL'
 
+      /**
+       * Null while the action attempt is pending or when this value does not apply.
+       */
       error: {
         /**
          * Detailed description of the error. Provides insights into the issue and potentially how to rectify it.
@@ -110,10 +111,9 @@ export type ActionAttempt =
           | 'encoder_not_online'
           | 'encoder_communication_timeout'
           | 'bridge_disconnected'
-      }
-
+      } | null
       /**
-       * Result of scanning a card. If the attempt was successful, includes a snapshot of credential data read from the physical encoder, the corresponding data stored on Seam and the access system, and any associated warnings.
+       * Result of scanning a card. If the attempt was successful, includes a snapshot of credential data read from the physical encoder, the corresponding data stored on Seam and the access system, and any associated warnings. Null while the action attempt is pending or when this value does not apply.
        */
       result: {
         /**
@@ -466,7 +466,7 @@ export type ActionAttempt =
            */
           warning_message: string
         }>
-      }
+      } | null
 
       status: 'success' | 'pending' | 'error'
     }
@@ -481,6 +481,9 @@ export type ActionAttempt =
        */
       action_type: 'ENCODE_CREDENTIAL'
 
+      /**
+       * Null while the action attempt is pending or when this value does not apply.
+       */
       error: {
         /**
          * Detailed description of the error. Provides insights into the issue and potentially how to rectify it.
@@ -501,10 +504,9 @@ export type ActionAttempt =
           | 'bridge_disconnected'
           | 'encoding_interrupted'
           | 'credential_deleted'
-      }
-
+      } | null
       /**
-       * Result of an encoding attempt. If the attempt was successful, includes the credential data that was encoded onto the card.
+       * Result of an encoding attempt. If the attempt was successful, includes the credential data that was encoded onto the card. Null while the action attempt is pending or when this value does not apply.
        */
       result: {
         /**
@@ -755,7 +757,7 @@ export type ActionAttempt =
          * ID of the workspace that contains the [credential](https://docs.seam.co/low-level-apis/access-systems/managing-credentials).
          */
         workspace_id: string
-      }
+      } | null
 
       status: 'success' | 'pending' | 'error'
     }
@@ -770,6 +772,9 @@ export type ActionAttempt =
        */
       action_type: 'SCAN_TO_ASSIGN_CREDENTIAL'
 
+      /**
+       * Null while the action attempt is pending or when this value does not apply.
+       */
       error: {
         /**
          * Detailed description of the error. Provides insights into the issue and potentially how to rectify it.
@@ -783,10 +788,9 @@ export type ActionAttempt =
           | 'uncategorized_error'
           | 'action_attempt_expired'
           | 'no_credential_on_encoder'
-      }
-
+      } | null
       /**
-       * Result of a scan to assign attempt. If the attempt was successful, includes the credential data that was scanned and assigned.
+       * Result of a scan to assign attempt. If the attempt was successful, includes the credential data that was scanned and assigned. Null while the action attempt is pending or when this value does not apply.
        */
       result: {
         /**
@@ -1039,7 +1043,7 @@ export type ActionAttempt =
          * ID of the workspace that contains the [credential](https://docs.seam.co/low-level-apis/access-systems/managing-credentials).
          */
         workspace_id: string
-      }
+      } | null
 
       status: 'success' | 'pending' | 'error'
     }
@@ -1054,6 +1058,9 @@ export type ActionAttempt =
        */
       action_type: 'ASSIGN_CREDENTIAL'
 
+      /**
+       * Null while the action attempt is pending or when this value does not apply.
+       */
       error: {
         /**
          * Detailed description of the error. Provides insights into the issue and potentially how to rectify it.
@@ -1067,10 +1074,9 @@ export type ActionAttempt =
           | 'uncategorized_error'
           | 'action_attempt_expired'
           | 'credential_not_found'
-      }
-
+      } | null
       /**
-       * Result of assigning a credential. If successful, includes the updated access method with the assigned credential.
+       * Result of assigning a credential. If successful, includes the updated access method with the assigned credential. Null while the action attempt is pending or when this value does not apply.
        */
       result: {
         /**
@@ -1241,7 +1247,7 @@ export type ActionAttempt =
          * ID of the Seam workspace associated with the access method.
          */
         workspace_id: string
-      }
+      } | null
 
       status: 'success' | 'pending' | 'error'
     }
@@ -1257,7 +1263,7 @@ export type ActionAttempt =
       action_type: 'RESET_SANDBOX_WORKSPACE'
 
       /**
-       * Error associated with the action.
+       * Error associated with the action. Null while the action attempt is pending or when this value does not apply.
        */
       error: {
         /**
@@ -1269,12 +1275,11 @@ export type ActionAttempt =
          * Type of the error.
          */
         type: string
-      }
-
+      } | null
       /**
-       * Result of the action.
+       * Result of the action. Null while the action attempt is pending or when this value does not apply.
        */
-      result: {}
+      result: {} | null
 
       status: 'success' | 'pending' | 'error'
     }
@@ -1290,7 +1295,7 @@ export type ActionAttempt =
       action_type: 'SET_FAN_MODE'
 
       /**
-       * Error associated with the action.
+       * Error associated with the action. Null while the action attempt is pending or when this value does not apply.
        */
       error: {
         /**
@@ -1302,12 +1307,11 @@ export type ActionAttempt =
          * Type of the error.
          */
         type: string
-      }
-
+      } | null
       /**
-       * Result of the action.
+       * Result of the action. Null while the action attempt is pending or when this value does not apply.
        */
-      result: {}
+      result: {} | null
 
       status: 'success' | 'pending' | 'error'
     }
@@ -1323,7 +1327,7 @@ export type ActionAttempt =
       action_type: 'SET_HVAC_MODE'
 
       /**
-       * Error associated with the action.
+       * Error associated with the action. Null while the action attempt is pending or when this value does not apply.
        */
       error: {
         /**
@@ -1335,12 +1339,11 @@ export type ActionAttempt =
          * Type of the error.
          */
         type: string
-      }
-
+      } | null
       /**
-       * Result of the action.
+       * Result of the action. Null while the action attempt is pending or when this value does not apply.
        */
-      result: {}
+      result: {} | null
 
       status: 'success' | 'pending' | 'error'
     }
@@ -1356,7 +1359,7 @@ export type ActionAttempt =
       action_type: 'ACTIVATE_CLIMATE_PRESET'
 
       /**
-       * Error associated with the action.
+       * Error associated with the action. Null while the action attempt is pending or when this value does not apply.
        */
       error: {
         /**
@@ -1368,12 +1371,11 @@ export type ActionAttempt =
          * Type of the error.
          */
         type: string
-      }
-
+      } | null
       /**
-       * Result of the action.
+       * Result of the action. Null while the action attempt is pending or when this value does not apply.
        */
-      result: {}
+      result: {} | null
 
       status: 'success' | 'pending' | 'error'
     }
@@ -1389,7 +1391,7 @@ export type ActionAttempt =
       action_type: 'SIMULATE_KEYPAD_CODE_ENTRY'
 
       /**
-       * Error associated with the action.
+       * Error associated with the action. Null while the action attempt is pending or when this value does not apply.
        */
       error: {
         /**
@@ -1401,12 +1403,11 @@ export type ActionAttempt =
          * Type of the error.
          */
         type: string
-      }
-
+      } | null
       /**
-       * Result of the action.
+       * Result of the action. Null while the action attempt is pending or when this value does not apply.
        */
-      result: {}
+      result: {} | null
 
       status: 'success' | 'pending' | 'error'
     }
@@ -1422,7 +1423,7 @@ export type ActionAttempt =
       action_type: 'SIMULATE_MANUAL_LOCK_VIA_KEYPAD'
 
       /**
-       * Error associated with the action.
+       * Error associated with the action. Null while the action attempt is pending or when this value does not apply.
        */
       error: {
         /**
@@ -1434,12 +1435,11 @@ export type ActionAttempt =
          * Type of the error.
          */
         type: string
-      }
-
+      } | null
       /**
-       * Result of the action.
+       * Result of the action. Null while the action attempt is pending or when this value does not apply.
        */
-      result: {}
+      result: {} | null
 
       status: 'success' | 'pending' | 'error'
     }
@@ -1455,7 +1455,7 @@ export type ActionAttempt =
       action_type: 'PUSH_THERMOSTAT_PROGRAMS'
 
       /**
-       * Error associated with the action.
+       * Error associated with the action. Null while the action attempt is pending or when this value does not apply.
        */
       error: {
         /**
@@ -1467,12 +1467,11 @@ export type ActionAttempt =
          * Type of the error.
          */
         type: string
-      }
-
+      } | null
       /**
-       * Result of the action.
+       * Result of the action. Null while the action attempt is pending or when this value does not apply.
        */
-      result: {}
+      result: {} | null
 
       status: 'success' | 'pending' | 'error'
     }
@@ -1488,7 +1487,7 @@ export type ActionAttempt =
       action_type: 'CONFIGURE_AUTO_LOCK'
 
       /**
-       * Error associated with the action.
+       * Error associated with the action. Null while the action attempt is pending or when this value does not apply.
        */
       error: {
         /**
@@ -1500,12 +1499,11 @@ export type ActionAttempt =
          * Type of the error.
          */
         type: string
-      }
-
+      } | null
       /**
-       * Result of the action.
+       * Result of the action. Null while the action attempt is pending or when this value does not apply.
        */
-      result: {}
+      result: {} | null
 
       status: 'success' | 'pending' | 'error'
     }
@@ -1521,7 +1519,7 @@ export type ActionAttempt =
       action_type: 'SYNC_ACCESS_CODES'
 
       /**
-       * Error associated with the action.
+       * Error associated with the action. Null while the action attempt is pending or when this value does not apply.
        */
       error: {
         /**
@@ -1533,12 +1531,11 @@ export type ActionAttempt =
          * Type of the error.
          */
         type: string
-      }
-
+      } | null
       /**
-       * Result of the action.
+       * Result of the action. Null while the action attempt is pending or when this value does not apply.
        */
-      result: {}
+      result: {} | null
 
       status: 'success' | 'pending' | 'error'
     }
@@ -1554,7 +1551,7 @@ export type ActionAttempt =
       action_type: 'CREATE_ACCESS_CODE'
 
       /**
-       * Error associated with the action.
+       * Error associated with the action. Null while the action attempt is pending or when this value does not apply.
        */
       error: {
         /**
@@ -1566,17 +1563,16 @@ export type ActionAttempt =
          * Type of the error.
          */
         type: string
-      }
-
+      } | null
       /**
-       * Result of the action.
+       * Result of the action. Null while the action attempt is pending or when this value does not apply.
        */
       result: {
         /**
          * Created access code.
          */
         access_code: Record<string, unknown>
-      }
+      } | null
 
       status: 'success' | 'pending' | 'error'
     }
@@ -1592,7 +1588,7 @@ export type ActionAttempt =
       action_type: 'DELETE_ACCESS_CODE'
 
       /**
-       * Error associated with the action.
+       * Error associated with the action. Null while the action attempt is pending or when this value does not apply.
        */
       error: {
         /**
@@ -1604,12 +1600,11 @@ export type ActionAttempt =
          * Type of the error.
          */
         type: string
-      }
-
+      } | null
       /**
-       * Result of the action.
+       * Result of the action. Null while the action attempt is pending or when this value does not apply.
        */
-      result: {}
+      result: {} | null
 
       status: 'success' | 'pending' | 'error'
     }
@@ -1625,7 +1620,7 @@ export type ActionAttempt =
       action_type: 'UPDATE_ACCESS_CODE'
 
       /**
-       * Error associated with the action.
+       * Error associated with the action. Null while the action attempt is pending or when this value does not apply.
        */
       error: {
         /**
@@ -1637,17 +1632,16 @@ export type ActionAttempt =
          * Type of the error.
          */
         type: string
-      }
-
+      } | null
       /**
-       * Result of the action.
+       * Result of the action. Null while the action attempt is pending or when this value does not apply.
        */
       result: {
         /**
          * Updated access code.
          */
         access_code?: Record<string, unknown> | undefined
-      }
+      } | null
 
       status: 'success' | 'pending' | 'error'
     }
@@ -1663,7 +1657,7 @@ export type ActionAttempt =
       action_type: 'CREATE_NOISE_THRESHOLD'
 
       /**
-       * Error associated with the action.
+       * Error associated with the action. Null while the action attempt is pending or when this value does not apply.
        */
       error: {
         /**
@@ -1675,17 +1669,16 @@ export type ActionAttempt =
          * Type of the error.
          */
         type: string
-      }
-
+      } | null
       /**
-       * Result of the action.
+       * Result of the action. Null while the action attempt is pending or when this value does not apply.
        */
       result: {
         /**
          * Created noise threshold.
          */
         noise_threshold: Record<string, unknown>
-      }
+      } | null
 
       status: 'success' | 'pending' | 'error'
     }
@@ -1701,7 +1694,7 @@ export type ActionAttempt =
       action_type: 'DELETE_NOISE_THRESHOLD'
 
       /**
-       * Error associated with the action.
+       * Error associated with the action. Null while the action attempt is pending or when this value does not apply.
        */
       error: {
         /**
@@ -1713,12 +1706,11 @@ export type ActionAttempt =
          * Type of the error.
          */
         type: string
-      }
-
+      } | null
       /**
-       * Result of the action.
+       * Result of the action. Null while the action attempt is pending or when this value does not apply.
        */
-      result: {}
+      result: {} | null
 
       status: 'success' | 'pending' | 'error'
     }
@@ -1734,7 +1726,7 @@ export type ActionAttempt =
       action_type: 'UPDATE_NOISE_THRESHOLD'
 
       /**
-       * Error associated with the action.
+       * Error associated with the action. Null while the action attempt is pending or when this value does not apply.
        */
       error: {
         /**
@@ -1746,17 +1738,16 @@ export type ActionAttempt =
          * Type of the error.
          */
         type: string
-      }
-
+      } | null
       /**
-       * Result of the action.
+       * Result of the action. Null while the action attempt is pending or when this value does not apply.
        */
       result: {
         /**
          * Updated noise threshold.
          */
         noise_threshold: Record<string, unknown>
-      }
+      } | null
 
       status: 'success' | 'pending' | 'error'
     }
diff --git a/test/seam/connect/resource-types.test.ts b/test/seam/connect/resource-types.test.ts
index 5a8a1f1f..4bec08f2 100644
--- a/test/seam/connect/resource-types.test.ts
+++ b/test/seam/connect/resource-types.test.ts
@@ -2,7 +2,10 @@ import test from 'ava'
 
 import type {
   AccessCode,
+  ActionAttempt,
   Device,
+  FailedActionAttempt,
+  SucceededActionAttempt,
   UnmanagedAccessCode,
 } from '@seamapi/http/connect'
 
@@ -29,6 +32,34 @@ test('access code resources narrow on is_managed', (t) => {
   t.is(typeof assertAccessCodeNarrowing, 'function')
 })
 
+const assertActionAttemptNullability = (actionAttempt: ActionAttempt): void => {
+  expectType<object | null>(actionAttempt.error)
+  expectType<object | null>(actionAttempt.result)
+
+  // @ts-expect-error The result is null unless the action attempt succeeded.
+  Object.keys(actionAttempt.result)
+
+  // @ts-expect-error The error is null unless the action attempt failed.
+  expectType<string>(actionAttempt.error.message)
+}
+
+const assertResolvedActionAttemptNarrowing = (
+  succeeded: SucceededActionAttempt<ActionAttempt>,
+  failed: FailedActionAttempt<ActionAttempt>,
+): void => {
+  expectType<object>(succeeded.result)
+  expectType<null>(succeeded.error)
+
+  expectType<string>(failed.error.message)
+  expectType<string>(failed.error.type)
+  expectType<null>(failed.result)
+}
+
+test('action attempt error and result are null unless resolved', (t) => {
+  t.is(typeof assertActionAttemptNullability, 'function')
+  t.is(typeof assertResolvedActionAttemptNarrowing, 'function')
+})
+
 const assertCustomMetadataValueTypes = (device: Device): void => {
   expectType<Record<string, string | boolean>>(device.custom_metadata)
 
diff --git a/test/seam/connect/wait-for-action-attempt.test.ts b/test/seam/connect/wait-for-action-attempt.test.ts
index ffa8e4ef..3ad77714 100644
--- a/test/seam/connect/wait-for-action-attempt.test.ts
+++ b/test/seam/connect/wait-for-action-attempt.test.ts
@@ -1,5 +1,6 @@
 import test from 'ava'
 import { getTestServer } from 'fixtures/seam/connect/api.js'
+import nock from 'nock'
 
 import {
   SeamActionAttemptFailedError,
@@ -205,6 +206,38 @@ test('waitForActionAttempt: times out if waiting for polling interval', async (t
   t.deepEqual(err?.actionAttempt, actionAttempt)
 })
 
+test('waitForActionAttempt: rejects when a failed action attempt has no error object', async (t) => {
+  const { seed, endpoint } = await getTestServer(t)
+
+  const seam = SeamHttp.fromApiKey(seed.seam_apikey1_token, { endpoint })
+
+  nock(endpoint)
+    .post('/locks/unlock_door')
+    .reply(200, {
+      action_attempt: {
+        action_attempt_id: 'e2192660-0e45-4a11-9800-eb4d086cca09',
+        action_type: 'UNLOCK_DOOR',
+        status: 'error',
+        error: null,
+        result: null,
+      },
+    })
+
+  const err = await t.throwsAsync(
+    async () =>
+      await seam.locks.unlockDoor(
+        { device_id: seed.august_device_1 },
+        { waitForActionAttempt: true },
+      ),
+    {
+      instanceOf: SeamActionAttemptFailedError,
+      message: 'Action attempt failed',
+    },
+  )
+
+  t.is(err?.code, 'unknown')
+})
+
 test('waitForActionAttempt: stops polling after the timeout', async (t) => {
   const { seed, endpoint } = await getTestServer(t)