I was checking out one of my company's website's Webmaster Tools to analyze the cause behind some soft 404 errors and discovered that a few of the older errors had affiliate mp referral tags listed as the relative URLs. Since these are older problems and I don't seem too many of them coming up in the last few months I don't think it's still a problem. I'm just curious if it's possible to cause a soft 404 by improperly copying the campaign or referral tag into the URL.
In some MVC, campaign trackers can soft 404 during a platform side route/redirect even if the campaign rewrite on url was successful. I can think of one popular ecom platform that does this causing false 404 positives on every single tracker rewrite it makes.
It can straight break the redirect too if its a software side thing. If the page is generated from query, and query fails from misunderstood URi, it could result in a header/footer loading a blank body (not even a 404) in which case google would think its soft 404.
Can you log your requests/rewrites to see whats up or would that crush your server?