# Exception: Key found in event is not documented! **URL:** \ **Category:** Beats\ **Tags:** filebeat\ **Created:** [August 6, 2021, 2:44pm UTC](https://discuss.elastic.co/t/exception-key-found-in-event-is-not-documented/280658 "2021-08-06T14:44:33Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![Jerry\_Tian](https://avatars.discourse-cdn.com/v4/letter/j/b38774/32.png) [@Jerry\_Tian](https://discuss.elastic.co/u/Jerry_Tian)\ **Post date:** [August 6, 2021, 2:44pm UTC](https://discuss.elastic.co/t/exception-key-found-in-event-is-not-documented/280658/1 "2021-08-06T14:44:33Z")
I am at step 5 of the testing phase in creating a custom filebeat module as detailed here [Creating a New Filebeat Module | Beats Developer Guide [master] | Elastic](https://www.elastic.co/guide/en/beats/devguide/current/filebeat-modules-devguide.html). However, I failed the test with the following short test summary info `FAILED tests/system/test_modules.py::Test::test_fileset_file_0_executor - Exception: Key 'heroName' found in event is not documented!` Any help will be appreciated! ---
**Author:** ![legoguy1000](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/legoguy1000/32/54301_2.png) [@legoguy1000](https://discuss.elastic.co/u/legoguy1000)\ **Post date:** [August 10, 2021, 11:36pm UTC](https://discuss.elastic.co/t/exception-key-found-in-event-is-not-documented/280658/2 "2021-08-10T23:36:35Z")
U need to add the `heroName` field to the `fields.yaml` file under the `_meta` dir at the root of the module. ---
**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\ **Post date:** [September 8, 2021, 1:37am UTC](https://discuss.elastic.co/t/exception-key-found-in-event-is-not-documented/280658/3 "2021-09-08T01:37:01Z")
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