DB Connect 3: Why am I getting error "failed to fetch" when I edit or clone a DB Input?

[aaronbarry73]

I just upgraded two heavy forwarders from DB Connect 3.0.0 to 3.1.3. On both forwarders, I can create a new input and save it. But if I try to clone an input and save, or edit an existing input and save, the "Finish", the screen hangs for 30-60 seconds before an orange banner shows the error "Failed to fetch". The input never saves. Does not appear to be driver-specific.
I am able to use the CLI to edit db_inputs.conf.
I don't see any errors in the internal logs, not sure if boosting the logging level will show an error? Has anyone seen this?

To be fair, I had a similar problem saving before, while using DB Connect 3.0.0, but only about half of the time. In 3.0, there was no error visible, except when I click back to the query screen I would see good query results, but an "undefined" error was displayed below the results...

[aaronbarry73 · Accepted solution]

Adding an answer, although this post is old...

This appeared to be an issue between Splunk and Chrome. Using Chrome debugger, I could see that Splunk may have been attempting to open more than 6 connections (sockets??), and Chrome only allows 6. This error did not occur in IE or Firefox, which both allow more connections, like ~13.

We updated Splunk to the latest version at the time, which I think was 7.1. The problem persisted. I made sure to use Firefox after this, when making edits in DB Connect. Eventually, I tried again in Chrome and there is no issue. Not sure if an update to Chrome fixed this, or an update to DB Connect, or something else.