General Troubleshooting

If you are running into problems starting a sim or more general website problems (network connectivity error, "an error occurred", "Seri didn't handle this error"), there are a variety of troubleshooting steps to take before contacting support.

Try force reloading the website. In most cases, Ctrl-Shift-R will perform a full reload.
Try doing a a full site reset using the Raidbots Reset tool.
Try using an incognito/private window. If this fixes the problem, the issue is probably a browser extension/plugin.
Try using a different web browser. If this fixes the problem, the issue is probably a browser extension/plugin.
If possible, try using another computer or phone that you have available on the same network. If this works, there's probably some other 3rd party software on your computer causing the issue.
If possible, try using another internet connection (cellular if you have a phone, neighbor's wifi if available, etc). If this solves the problem, there may be an issue with your network provider or a connectivity issue between you and the Raidbots servers
Pause/disable any 3rd party anti-virus/anti-malware software running. These can sometimes incorrectly categorize Raidbots traffic as a problem.
Pause/disable any VPN software you are using. These can sometimes cause network issues with Raidbots.
Alternatively, try using a VPN to a different country/location. If this works, there's probably some issue with your ISP.
Pause/disable any 3rd party Crypto software. These can do all kinds of weird/bad things.
Run anti-malware (like Malwarebytes) on your computer to clean up any possible malware.

Some common known issues:

Intel Killer Intelligence Center - disable the "Prioritization Engine" and/or uninstall the program entirely. This is known to break sims on Raidbots.
NordVPN Threat Protection - this is known to cause some issues with various WoW-related websites. Disable it and try again.

If you are still having problems, please contact Raidbots Support and include a browser network trace (HAR file). Please include the browser(s) you have tried, the PC/phones you have tried (device type, OS, etc), the country you are in, your residential and/or cellular network providers that were tested, and any additional info you can come up with.

These types of problems are extremely difficult for Raidbots to diagnose so please provide as many details as possible.