Putty network error connection refused

One of my Raspberry Pi’s that performs sump pump depth measurements every 5 minutes works headlessly. Last week it stopped supplying values via the network to my other Pi, which does the reporting via a web page.

So I tried to reach the Pi via putty. Putty responded with “network error connection refused”. This led me to checking cables, and I found that everything was fine. To make a long story short, it turned out that a recent power loss must have caused a corruption within the networking setup of the Pi.

I hooked up a monitor, keyboard and mouse and did a “sudo apt-get update” followed by “sudo apt-get upgrade”, followed by “sudo apt-get upgrade --fix-missing”. Lastly, I reset the SSH keys by issuing “sudo rm /etc/ssh/ssh_host_*” followed by “sudo dpkg-reconfigure openssh-server”.

After this, things were back to normal.