Browsers

Is the problem one website or the browser itself?

Check another page in the same browser and record the affected address and error. Compare the result in another supported browser when available. A site outage, connection problem and local browser setting need different fixes.

What should I check before clearing browser data?

Check which data will be removed. Clearing cookies can sign the user out, and clearing saved data can remove information they expect to keep. Choose the narrowest relevant change, then retest the affected website before resetting the whole browser.