TL;DR: I feel like an incompetent imposter who was just exposed. It doesn't seem like major issues, but I feel like I just lost nuclear codes in the subway.

Part of my job is that I do accessibility tests of websites and apps. For two development teams of a customer, I help during development, identifying issues so they can be fixed before deployment.

Now it's a pretty big customer, with lots of users. I had a slip a few months ago where a complaint about an accessibility issue came in that I should definitely have caught. It was quite embarassing for me, though I didn't get shouted at for it.

And now the same is happening for the other customer. I know a complaint is coming in, and while not massive and in fact the customer probably won't fix it at all, it is something I definitely should have caught.

I'm gutted, and I am really considering retreating from the whole accessibility topic (I am also a developer, so it isn't the only thing I do at my job). My employer wouldn't be thrilled though, because I just made another certificate (on their money) and am listed as project lead in an offer for another accessibilty topic with another customer.

With software bugs in my code, I barely have that feeling, because everyone expects bugs. I rarely care, I'm just in problem solving mode. But with accessibility reviews, it seems to me customers expect a complete, thorough, flawless report.

Don't get me wrong, I find plenty of issues in their products and report them accordingly, but I feel totally inadequate to guarantee a report without anything missing.

I can argue with myself all I want - that mistakes are normal, that tens of thousands of users are more likely to catch something than I am on my own - but still I feel absolutely gutted and incompetent.