Disregard my previous post, I failed to see that you did mention that it was an STL file.
Out of curiosity though, I attempted to upload a file I know to be over a million polygons and was brought to this link:
https://www.shapeways.com/upload
When it brought me there, I saw an error message, so I copied and pasted the URL into a new window and it redirected me to
https://www.shapeways.com/create. If you try clicking that '/upload' link above, it will also redirect you to the same '/create' page. It's possible that your browser automatically refreshed the page during the upload, or when it failed, and you were redirected as a result.
On a side note not entirely unrelated, when I tried to upload it again so I could screen grab the error message, the model successfully uploaded lol. I guess if you're persistent enough, it ignores the 1 million polygon limit. This may be another bug...