[OJS 3.1.2] Add Reviewer Form and Accept Submission Form couldnt be saved

I tried to add a reviewer but form couldnt be saved (Spinner keep loading)
image

and so does when i tried to accept the submission
image

i open the chrome inspection and this is what it showed
image

and here is the log of the server
image

Ive followed this guide too but still the problem persist Submission metadata form: pressing save button triggers browser errors · Issue #4072 · pkp/pkp-lib · GitHub

edited: found another same issue when submitting an article
image

Please help me to solve it, your help will be much appreciated, thanks