Why is the searchTasks endpoint returning an invalid JSON from very large requests?
Though no official size limit has been published, PAS will return a misleading invalid JSON error if you send in several thousand search terms at once. The exact maximum seems to vary across different installs. We have logged a story in our backlog about making a more explicit size limit possible, but there is no current plan to allow for PrizmDoc to handle search requests of unbounded size.
The best workaround for this behavior is to split your search terms between multiple requests, rather than packing them into one request.