What is the name of the domain?
What is the issue you’re encountering
When attempting to create a WAF rule with a custom expression it is very easy to accidentally have syntax errors. This makes sense as it is freeform text input and that is my fault. The problem is that the error for any syntax errors shows up after a page redirect which wipes out all text that was in the custom expression, so unless you copy the expression before attempting to submit then you lose all edits or perhaps the entire expression if it was a new submission. This is a bit silly, it seems like it would be simple enough to wait for the server response and show the error message without wiping out the input fields so that I can find and fix my syntax error without having to rewrite it from scratch
What are the steps to reproduce the issue?
Create a WAF custom rule, add a title, click ‘edit expression’ to get a free-form expression box. Then enter an expression with an invalid syntax. Set the action type to anything. Attempt to submit the rule, the page will be redirected to a blank rule entry form and then an error will appear for a few seconds at the bottom of the page.