The yellow triangle usually indicates the icefaces/ajax connection used to update page status was broken, either due to something network related or possibly a timeout.
So, when you select a file to upload, the file upload has actually begun and the page refreshes with the file in the list when it has completed. This is separate from ingest where additional processing is performed on certain file types after upload to extract
A few things to consider:
1. Try a small text file that should be quick to upload and not undergo any additional processing, this should work.
2. The file that is failing is Stata, which will undergo additional processing. At this stage the type should not be an issue. What size is this file? How long was it uploading before the yellow triangle appeared?
3. Try running your browser's debug console while it is happening and watch for network activity. I'm assuming there will be a network error when the triangle appears.
4. Is there a proxy anywhere between your browser and the server? Some proxies by default do not handle the ajax headers properly and so drop them, causing file upload issues.
5. While running your test, tail -F server.log and watch for any errors. I did see an warning with a reference to Faces but not sure what it means.
6. Last, it does not seem like it has anything to do with Postgres but we have not tested v3.6.2 against Postgres 9.3. My understanding from the Postgres support page is minor versions are fully compatible, major versions may have some data type differences.
Sorry that I do not have a definite answer. I hope the ideas point you in the right direction.