Hello,
I been running into this issue and cant figure out what is wrong. Every time I make a small change in one of the nodes or in this case Slack node, it gives me this error:
Same thing happens if I make it inactive. This started after one of the updates I believe, I didn’t make any changes for a while and all of the sudden I cant edit one of my big workflows and I created this one as a test, it was saving fine for some time until I added https:// line. Same thing happens if I add new slack node and just add credentials.
Is it really only when using that url in a workflow? My first thought on seeing that error is there could be a reverse proxy between you and n8n which is doing something funky.
We running this in AWS and have EC2 Rules set up to guide the webhook to the right spot. I did some testing over the weekend and seems like I was able to get it back working with new instance that doesnt have any of the rules for webhooks. Do you think something is off with HTTPS:443 routes? What confuses me the most is that it saves while i start new workflow and keep adding nodes, but soon as I add HTTP or slack node at the end of my workflow it gives me that error.