Internet connection
Sometimes the cause is a bad internet connection or there is a malfunction with your internet provider. If the application does not work (properly) on your current network, try using a different WiFi, 4G or 5G connection.
Browser
The error message may only appear in the specific web browser you are using. Try to see if it works fine in another browser - such as Edge, FireFox, Chrome or Safari.
Private or incognito window
Sometimes a problem has to do with user history, such as cookies, your browsing history or previously entered data (for example in a form). By doing the same thing in a private or incognito window, you'll find out if this is the cause of the problem.
Device
In some cases, a problem is caused by (settings on) the device you are using. Try it with another smartphone, computer or tablet.
Location / IP address
Some restricted pages are only accessible from certain locations. The failure of a page may be due to an IP restriction. A handy link to find out your IP address is http://watismijnip.nl/.
Staging, test or live URL
Are you viewing the page at the correct URL? The problem may be because you are not using the correct web address. Check if you are on the right staging, test or live URL.
Cookies
A problem can be caused by cookies or caching. Always refresh the page first. Just refreshing with F5 (Mac: Command + R) is often not enough. With a 'hard refresh' (Windows: Ctrl + F5 / Mac: Command + Shift + R) you remove all caching and cookies.