# Unknown property used in expression ${action=='submit'}

**URL:** <https://forum.flowable.org/t/unknown-property-used-in-expression-action-submit/5566>\
**Category:** Flowable Engine\
**Created:** [March 5, 2020, 6:15am UTC](https://forum.flowable.org/t/unknown-property-used-in-expression-action-submit/5566 "2020-03-05T06:15:04Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![cnaru](https://avatars.discourse-cdn.com/v4/letter/c/9d8465/32.png) [@cnaru](https://forum.flowable.org/u/cnaru)\
**Post date:** [March 5, 2020, 6:15am UTC](https://forum.flowable.org/t/unknown-property-used-in-expression-action-submit/5566/1 "2020-03-05T06:15:04Z")

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When calling url /platform-api/process-instances, I am getting the error unknown property used in the expression. How do I pass the property to the rest api

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**Author:** ![joram](https://yyz1.discourse-cdn.com/flex035/user_avatar/forum.flowable.org/joram/32/26_2.png) [@joram](https://forum.flowable.org/u/joram)\
**Post date:** [March 14, 2020, 1:57pm UTC](https://forum.flowable.org/t/unknown-property-used-in-expression-action-submit/5566/2 "2020-03-14T13:57:25Z")

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Depends on what kind of expression you are using. If it’s a regular variable, you will need to pass the variable with the REST request you use to start the process instance, complete the task, etc.