1. I want to write, but this part is just so boring, I can't even force myself through it to get to the next good part.

Maybe....don't write it if it's that boring?

If even you are bored, think how bored the reader will be! You probably don't need the boring bit anyway. Write something exciting there instead. Or write a one-line summary of what happened and then skip to the good part.

2. I want to write, but I don't know how to write the transition from this part to the next part.

Maybe... don't write it if all you want to do is get to the next part?

You don't have to write a smooth, complete ending and beginning to every bit. That's what double line spaces and rows of stars and chapter breaks are for. Or "And [x] [time] later" at the beginning of the next paragraph.

3. I want to write, but I don't know what comes next, only what comes after that.

Maybe... don't write it if you don't know what happens?

What happens next clearly isn't vital to the story, if you don't know but you know what happens after that. Skip to the part you do know, or write a one-line summary and move on. And if it does turn out that what happened is important later, you can always do it as a flashback or edit it in.

4. I want to write, but there's something in the next paragraph that I need research for, and I can't find the answer anywhere.

Maybe... don't write it if you can't find the answer?

If ten minutes with Google skill doesn't get an answer, chances are most of your readers won't know either. Long research jags are for a) fun or for b) things that will have a large effect on the piece overall, not for one line of description. Leave it out. Or if the POV really should know the answer, come up with a reason why they don't, and that's characterization/worldbuilding/plothook. Or make up the answer, and if it later turns out to be completely wrong, that's characterization/worldbuilding/plothook too.

5. I want to write, but this particular part is going nowhere and everything I write seems wrong.

Maybe... don't write it if it seems wrong?

This is often your writer brain telling you that you're writing the wrong thing. Go back to where it started feeling wrong, get rid of everything after that, and come up with something completely different you could write there instead. Or write a one-line summary to close it off, and move on to something else.

X. I want to write this, but it's a new project and it's going to be long and I have a lot going already and I should focus on those, and I don't think I'm ready to start it anyway

Maybe... don't write it if SCREW YOU I WRITE WHAT I WANT IF I CAN'T START THIS I'M NOT WRITING ANYTHING EVER AGAIN SO THERE