"ROC - Update string Parameter" fails to update parameter with error:

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However the parameter does exist. Other actions such as "Set Parameter Value - String" updating the same parameter do complete well.

There are a number of conditions that need to be satisfied in order to let the "ROC - update .... parameter" actions succeed

Release Automation 5.5 and higher

Following conditions need to be met, given following parameters of the action:

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1. The Step's stage should be different than the stage the action actually runs in, so when the Step's stage is Deployment, the action should run in pre-Deployment. 
2. The parameter specified should be of type User Input
3. The parameter should be referenced in the Process that is invoked by Step Name
4. The Parameter Name should list the fully qualified parameter name excluding the qualifiers already listed in Step Name and Server Type name. E.g. is the parameter name is defined as:

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Then the full qualified name would be process2/Server Type 1/Default Component/sParm2

The action has filled in parameters for Step Name (referring to process2) and Server Type Name, so the Parameter Name to refer to is the remaining part: Default Component/sParm2