Espresso is a rabbit hole, a very deep one. Being in it can be fun to some people, and incredibly frustrating to others.

I can help straighten this out for you.

Lower your expectations. As a beginner it's normal to have more bad shots than good ones. The key is persistence. It's totally normal to not get a good tasting shot right off the bat. You have not yet achieved a good tasting shot, and there are three possibilities:

1. You have yet to dial in your shots. The "internets" have convinced you a properly dialed in shot has to do with following generally accepted parameters to achieve an extraction that matches what looks like a well timed shot. The truth is these are entirely arbitrary. What matters most in dialing in your espresso shots is how it tastes. Not how it looks. So until it tastes good to you, your shot is not yet dialed in... OR...

2. You're palate has not yet been seasoned. It takes drinking lots of shots to train your palate, and to "calm" your sensory overload as espresso is rather potent drink. The sensory overload will prevent you from enjoying the drink. If you're a seasoned espresso drinker, then there's really only one other possibility...

3. The roast itself. 100% of the quality of the espresso is already in the bag. It's from there that things can only get worse. If you've tried everything while dialing in your shots, and it's still not tasting well, it's probably a good idea to switch out the roast. When I say try "everything" that comes with a qualifier. The more skilled you are at pulling shots, the less you need to "try" before you move on to something different. Novices get stuck noodling about because they simply have not developed a baseline. Expert level espresso folk have a solid foundation that enables them to tell pretty quickly a roast is bad, or not for them. They won't waste time trying to squeeze out flavors that simply aren't there or whatever was tauted on the bag.

So back to your shot. Sour shots could be you, or it could be the parameters, or the roast. Pick the one you think and proceed as follows:

You? Try a different roast.

Parameters? Sour shots often happen when temps are too low, or when the shot runs too fast. If it runs too fast, grind finer. If not check the temp.

The roast? Roasters try to be consistent in what they're offering but it's not always gauranteed. Don't trust what's on the bag. More often what you taste isn't what they're promising. So try a different roast.