"errorDescHtml":"projectId is Invalid."

[Shiva Prasad Bhat]

I get this error when attempting to create a cycle using ZAPI API to create a new cycle. I am pretty sure I am using the right project ID.  Is there a way i can get the reason behind this?

I am doing a post 

{
"environment":"",
"startDate": "",
"versionId": "101008",
"endDate": "",
"name": "LCM Pipeline test cycle ZAPI",
"clonedCycleId": "",
"projectId":"21523",
"description": "Created In ZAPI",
"build": ""
}

[Jakub Vávra]

I did see the same error message and found Your question.
I know that this is quite an old topic but I will answer anyway for the benefit of others that hit this.
I managed to succeed by changing the method from GET to POST in my case.
It looks like there is a misleading error message that pops even for different type of issues.