diff --git a/schemas/json/layout/expression.schema.v1.json b/schemas/json/layout/expression.schema.v1.json
index 1fe72c015a..2dd61724fc 100644
--- a/schemas/json/layout/expression.schema.v1.json
+++ b/schemas/json/layout/expression.schema.v1.json
@@ -235,7 +235,11 @@
       "type": "array",
       "items": [
         { "const":  "authContext" },
-        { "enum": ["read", "write", "instantiate", "confirm", "sign", "reject"] }
+        { "anyOf": [
+          { "enum": ["read", "write", "instantiate", "confirm", "sign", "reject"] },
+          { "type": "string" }
+        ]}
+
       ],
       "additionalItems": false
     },
diff --git a/src/features/expressions/expression-functions.ts b/src/features/expressions/expression-functions.ts
index c5bd4b424a..39174725d5 100644
--- a/src/features/expressions/expression-functions.ts
+++ b/src/features/expressions/expression-functions.ts
@@ -23,7 +23,7 @@ import type {
 } from 'src/features/expressions/types';
 import type { ValidationContext } from 'src/features/expressions/validation';
 import type { IDataModelReference } from 'src/layout/common.generated';
-import type { IAuthContext, IInstanceDataSources } from 'src/types/shared';
+import type { IInstanceDataSources } from 'src/types/shared';
 import type { ExpressionDataSources } from 'src/utils/layout/useExpressionDataSources';
 
 type ArgsToActual<T extends readonly AnyExprArg[]> = {
@@ -407,22 +407,20 @@ export const ExprFunctionImplementations: { [K in ExprFunctionName]: Implementat
     return (this.dataSources.applicationSettings && this.dataSources.applicationSettings[key]) || null;
   },
   authContext(key) {
-    const authContextKeys: { [key in keyof IAuthContext]: true } = {
-      read: true,
-      write: true,
-      instantiate: true,
-      confirm: true,
-      sign: true,
-      reject: true,
-      complete: true,
-    };
-
-    if (key === null || authContextKeys[key] !== true) {
-      throw new ExprRuntimeError(this.expr, this.path, `Unknown auth context property ${key}`);
+    if (key === null) {
+      throw new ExprRuntimeError(this.expr, this.path, `Auth context key cannot be null`);
     }
 
     const authContext = buildAuthContext(this.dataSources.process?.currentTask);
-    return Boolean(authContext?.[key]);
+    const hasAction = authContext?.[key];
+    if (hasAction === undefined) {
+      throw new ExprRuntimeError(
+        this.expr,
+        this.path,
+        `Unknown Auth context property ${key} for task ${this.dataSources.process?.currentTask?.elementId} (allowed keys are {${Object.keys(authContext).join(', ')}})`,
+      );
+    }
+    return Boolean(hasAction);
   },
   component(id) {
     if (id === null) {
diff --git a/src/features/expressions/shared-tests/functions/authContext/error-unknown-action.json b/src/features/expressions/shared-tests/functions/authContext/error-unknown-action.json
new file mode 100644
index 0000000000..1e935209a0
--- /dev/null
+++ b/src/features/expressions/shared-tests/functions/authContext/error-unknown-action.json
@@ -0,0 +1,16 @@
+{
+  "name": "error unknown action",
+  "expression":  ["authContext", "unknown_action"],
+  "expectsFailure": "Unknown Auth context property unknown_action for task Task_1",
+  "permissions": {
+    "read": true,
+    "write": false,
+    "actions": {
+      "instantiate": true,
+      "confirm": true,
+      "sign": false,
+      "reject": false,
+      "asdf":false
+    }
+  }
+}
diff --git a/src/features/expressions/shared-tests/functions/authContext/read-sign.json b/src/features/expressions/shared-tests/functions/authContext/read-sign.json
index a674b8a053..31dbba3b66 100644
--- a/src/features/expressions/shared-tests/functions/authContext/read-sign.json
+++ b/src/features/expressions/shared-tests/functions/authContext/read-sign.json
@@ -14,7 +14,8 @@
     "actions": {
       "instantiate": true,
       "confirm": false,
-      "sign": true
+      "sign": true,
+      "reject": false
     }
   }
 }