Set Parent Link on Epic as Issue that triggered Rule in Automation

[David Blank]

I'm trying to set the "Parent Link" field on an Epic that I'm creating with automation. Parent Link does not show up in the list of available fields on Create Issue so I am using the Additional Fields JSON block to set it. 

I've tried a number of things and gotten two different errors. First I tried:

{
"fields": {
"parent Link": "{{issue.key}}."

}
}

Error: Error creating issue

Could not find issue by id or key. (parent)

And next I tried:

{
"update" : {
"customfield_<parentLink Field ID>" : [{"set" : "{{issue.key}}"}]
}
}

Error: Unknown fields set during create, they may be unavailable for the project/type. Check your custom field configuration. Fields ignored -

customfield_<parentLink Field ID>

I've grabbed the name and ID of the field to be sure I am referencing the name correctly. When that didn't work I tried making changes to casing.

I've confirmed that the Parent Link field is on the Issue create screen for Epic.

[Els Bassant]

I know that this question is from a while ago, but stumbled upon this question when I ran into the same issue.

I had success with the following Json:

{
    "fields": {
        "customfield_00000": "{{issue.key}}"
    }
}

Where "customfield_00000" uses the number of your custom field.

[Nic Brough -Adaptavist-]

Welcome to the Atlassian Community!

The question has confused me, the summary reads like you are trying to apply a parent to an Epic (so to a layer in Advanced Roadmaps above it).  But the body sounds more like you are trying to add a base-level issue into an Epic?

[David Blank]

Thank you for your question @Nic Brough -Adaptavist-

I am manually creating a "Highest Milestone" Issue.  The creation of an issue triggers my automation to create an epic and link that epic as the child of the "Highest Milestone" that triggered the automation.

[David Blank]