In most cases bad data related to adapter failures can safely be ignored. The examples below show some common failures.
"Querystring is empty: no raw event to process"
This is related to our monitoring mechanism of your collector which pings it every 5 minutes.
"field": "vendor/version", "value": ".well-known/dnt-policy.txt", "expectation": "vendor/version combination is not supported"
The error means that something has pinged the collector which is not a Snowplow tracker. In most cases will be a malicious bot.