I want to fill in a Issue Picker Field (single) with a fixed value with Automation

[Marco Brundel]

Hi,

I want to fill in a Scriptrunner Issue Picker Field (single)(customfield_14014) with a fixed value via an automation rule (key: ITS-12345).
I only get the error "Operation value must be a string (customfield_14014)".

What is wrong with my Json script?

The script is:

{
"update": {
"customfield_14014" : [
{
"set": {
"key":"ITS-12345"
}
}
]
}
}

Thank you in advance.

Regards, Marco