# System.MissingMethodException

**URL:** <https://discuss.workflowgen.com/t/system-missingmethodexception/854>\
**Category:** Development\
**Created:** [August 23, 2017, 12:57pm UTC](https://discuss.workflowgen.com/t/system-missingmethodexception/854 "2017-08-23T12:57:54Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![stebuch](https://avatars.discourse-cdn.com/v4/letter/s/8edcca/32.png) [@stebuch](https://discuss.workflowgen.com/u/stebuch)\
**Post date:** [August 23, 2017, 12:57pm UTC](https://discuss.workflowgen.com/t/system-missingmethodexception/854/1 "2017-08-23T12:57:54Z")

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i’m wondering what i’m doing wrong

as soon, as i add an UPDATEPROCESSDATA Action  
using \<WF\_PROCESS\_INST\_ID\> as Input to Parameter REQUEST\_ID  
im getting following error wile executing

```
Workflow error An error occurred while completing the action. Verify if the action has been completed. If not, then try again.
Stack Trace:System.MissingMethodException: Method not found: '!!0[] System.Array.Empty()'. at Advantys.Workflow.Engine.WorkflowsManager.ActivityInstanceComplete(Int32 processInstanceId, Int32 activityInstanceId, WorkflowUserIdentity connectedUserIdentity, WorkflowUserIdentity requesterUserIdentity) at Advantys.Workflow.Web.UI.Portal.ApplicationPages.ApplicationComplete(PageController pageController, KeyedList wfgParams)
```

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<div class="post-metadata">

**Author:** ![stebuch](https://avatars.discourse-cdn.com/v4/letter/s/8edcca/32.png) [@stebuch](https://discuss.workflowgen.com/u/stebuch)\
**Post date:** [August 24, 2017, 8:23am UTC](https://discuss.workflowgen.com/t/system-missingmethodexception/854/2 "2017-08-24T08:23:04Z")

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for those who are happening to get the same error, the solution was to install .net 4.6 on the server.