first the error from the log is not connected to your 500 loading error - because that is about ingesting a messages.
You tried quick values on the field message? That is a full text field and can contain really different kind of content. That is why this can fail - because the variance is to big. For that reason quick values on the message field is disabled.
For you - yes that can happen. You can only separate the data you are interested in to different fields and run the quick values on that.