it is hard for me to help you find a solution if you do not try the solutions i have already provided.
the error is coming from a call to json_encode. that method will return false if it can not properly encode the data provided to it. which most likely means that the data is not utf8 encoded.
i agree that i would be reluctant to implement a solution until i can accurately reproduce a problem; but given the frequency of your issue, i am not really sure what the downside is.
best.
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