We have serveral Jenkins masters at our company, all with the vSphere Plugin installed (v 2.15 and v2.16) which we use to dynamically start and stop VM's. This vSphere Plugin is connected to a vcenter host.
Most of the time this works well, however, when we experience a network drop or an VCenter issue which prevents the login to VCenter some of the masters with the managed slaves keep displaying the folowing error:
"Ignoring connect attempt to start the slave; it's being shutdown"
This error causes a problem because Jenkins is not able to start the slaves (which are either already off but sometimes still turned on).
We can resolve this by a safeRestart or go to the specific slave and in Configure do a Save (without actual changes to the configuration).