Name the service, exact action that failed, approximate local time with time zone, and the visible error. Say whether another browser or network behaves the same way and whether other features of the service still work. A broad region can be useful for regional failures.
Check official status information before assuming the issue is widespread; community reports can add context. If you attach a screenshot, remove email addresses, account IDs, payment details, tokens, and private messages. Do not post live links containing session parameters.
A precise symptom and a few safe comparisons help others reproduce the issue without exposing you.
Akousa