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 
lrtetala
Anil_G
james07
sven.wullum1
ijanszen1
vineelag
Monchello_Curry
Affan_Basar
Chimbu
Hemant_Deshmukh