If you're having problems with a driver, or an app, or other issues, there are plenty of people on the forums willing to help. To save some time and narrow down what your problem is, please:
What is the exact issue you are having? What error code(s) are you encountering? Did you recently change anything? (firmware, driver code update, device additions etc)
Specify Hubitat firmware, device OS and browser to help replicate the issue.
1a. The livelog isn't saved anywhere, so open it in a separate browser window or tab while troubleshooting errors.
Describe what troubleshooting steps you've already tried. Seriously, DO this. Nothing like having a whole bunch of people try to figure out an issue and the user isn't forthcoming about what they've already tried unless specifically asked about each one.
2a. For Z-wave devices, try a z-wave repair before excluding. (settings -> Z-wave Information -> Repair Z-Wave)
2b. for Zigbee devices, issues can occur with radio conflicts between wifi and zigbee. Overlap is detailed here:
Be patient. Some issues are harder to fix than others, and may take some time to deal with.
If it's a hub stability issue (error 500, or unable to access hub) contact support directly at firstname.lastname@example.org
If your area is prone to power fluctuation or outages (or even if it isn't) I highly recommend you have your internet modem, wifi router and Hubitat powered through a UPS. This could prevent a database corruption error from the hub suddenly losing power during a write.
If you're in the UK or Europe, your Hubitat comes with two dongles. Power off your Hubitat and insert both dongles to enable Z-Wave and Zigbee radios.