I’ve seen a few posts about this issue with the same resolution of logging out and back in of the orchestrator to fix but the only bug I see is for Add Queue Item of the same error.
I received this error after an unexpected reboot of a development server where as previously the project worked fine.
After consulting the magical oracle Google sending me to a closed post here with the resolution of simply relogging the orchestrator worked I just wanted to see if this has the right “hmm, this seems to be trending” tags 
ashokkarale
MD_Farhan1
Ajay_Mishra
postwick
Dheerendra_vishwakarma
Anil_G
chandreshsinh.jadeja
Gautham_Pattabiraman
vrdabberu
aravindbalineni123