I built this story around a prebuilt campaign to add more engagement for my players. I had 2 of 5 players (they were friends) leave my campaign last session 3 hours before it started. I had to hard pause the story as I was not prepared for such a transition and I didnt want to move the story along and create plot holes. I've been poking around for a substitute and messing around with transitionary ideas but I'm feeling super discouraged abut the entire thing. Is this normal? Not sure if I should push through or if I'm just not cut out for DMing. Anyone else experience this kinda thing? 

It's pretty normal. I have built storylines that had to be cut or rearranged as players left games before. Weirdly, you get better at it with practice, though it's not something you really want to be in the practice of.

Just push through. Keep what is salvageable and start fresh where you can't save the story. If the damage is beyond repair, just accept it and start up a new game.

I'm sorry you had a rough turn in your game.  It's completely normal and understandable to feel discouraged when folks leave a game abruptly.  You put in behind the scenes effort and the departure leaves you feeling abandoned.  It sucks.

If you put the effort into building or enhancing the world, you have the ability to adapt, since you've already adapted the world once.  What this gives you is a crash course in learning the mental/creative nimbleness and agility necessary for running most games.  Player commitment will always be an X factor, even among friends, because as much as they may be attracted or even to that moment invested in the game, they have a greater investment in "life stuff" (as they should).  Over the past year which was my "serious" return to gaming, I've DM'd for about 12 people over 3 groups.  I've had three players have to leave, two of which led to the shut down / or suspension of that game.  Rather than think of the work in the abandoned game as "rejected" that's worthless without those players, it gets filed away to be used when needed.  So going forward, rather than thinking about the materials you can't use now, think of them as resources to let set and maybe bring about again in the future.  Good DMs always have tricks like that available when their active games take a left turn.  That's not to invalidate how you're feeling now.  It's fine to feel disappointed, but rather than think of the ends as worthless, recognize that the investment you put in gave you an opportunity to exercise and grow your creative ability and that will benefit you in the long run if you keep DMing.  So keep your chin up, tell your friends you're sorry they can't play, and as one of my YouTube gurus says, roll with it ;)

echo what the others have said. don't take it personally. There are plenty of eager players on DDB that want to play. Just put the word out. in the meantime, keep going. add an NPC or two to keep the balance with your campaign.  I'd recommend doing that and let the other players run them if they are experienced enough to do so, otherwise run them yourself. Its better to do that than continually nerfing the campaign for 3 players. Give your players some extra experience points for carrying the added burden. they'll like that an cement them into your game.

Over the summer of 2020, I played D&D online with seven of my friends as the DM. Over time, three of them stopped playing and one of them became inconsistent. There was also a very long segment of time in the game that I should have sped up, but didn't. There were disagreements between myself and a few of the players, and it led to my scrapping the campaign, which was a prebuilt module, and started a completely new one, completely from my own self this time. I blame myself for the result of the first campaign, personally, but your situation is different and difficult in a completely different way. For your situation, I'd say move forward with the three players you have and build the story around them and their backstories (unless you get more players somehow). It can be annoying to have to change what you had planned, but it'll be more fun in general to not have to say, "Well, I was going to have a character from Player X's backstory show up, but they're not here," and instead have things work out the way you planned because you planned it around players that show up consistently.

I would definitely tell my players, if people are not going to show up consistently, then nobody should expect any custom stuff in the campaign about their characters. I can't spend hours making stuff up about your background and then you don't show up that session. If you want personal stuff about your character you have to show.

That’s awful, I’m so sorry!  Can you turn their characters into NPCs?  That might decrease the amount of changes you have to make to your game.

It's completely normal. The best group I've ever run with (multiple DM's, generally pretty consistent and open schedules, and responds promptly to scheduling usually), outside of a club, has had 5 campaigns fall though since we got together at the beginning of the pandemic. We've also lost 1, most likely 2, players since the group's inception.

It's a huge bummer but many groups have players that drop out and new players that pop in.

Don't take it personal. Everybody has their priority list and for some folk, D&D isn't high on the list (wth??).

I've been running the same campaign with four different groups over the course of a couple decades and from one game system (Fantasy HERO) to another (D&D 5e). Players come and go. In fact, one of the players from the first group dropped out and is now currently playing the newest group.

I've had games get canceled 40 minutes before start time because one of the players has something come up. It's super frustrating.  I haven't had to scrap an entire campaign yet, but sometimes it's tempting to just give up. Especially after a game gets rescheduled multiple times over a week just to get canned.

It happens. You're not alone.

Even if the ending doesn't turn out the way you'd hoped, at least the journey was fun, right?

My DM had to replace three members of our group, bud. You ain't alone in that! You're doing fine.

And people wonder why there is a shortage of DMs.

At this point, almost 60% of the DMs who have responded to this thread have had to scrap a game because people stopped showing up. That means the majority of DMs have had the experience of doing all that work, only to have to scrap it. How many people, having had that experience just once, would say "not going to do that again?" How many people, having had it more than once, will say the same?

One can easily see how many DMs don't persist, if such a high percentage of us have had to scrap games because players stopped showing up. There is an old saying I found in the very early days of the internet (I probably read it on the Netscape Navigator browser, that's how old it is): "The thing about beating your head into a brick wall, is that it feels so good when you stop."

Turnover in groups is extremely common. High school can be slightly more reliable but as soon as you hit higher education or the real world then there are MANY other aspects of life that can take priority - family, children, significant others, work, other activities, sports, other friends. The list is almost endless.

However, if you are on good terms, it would be useful for you to know why your friends left. Are they busy in real life? Do they have the time to play? Are they having fun? Pressure from significant others to spend more time with them and less with gaming buddies?

The only answer you should likely be concerned about is if they stopped because they aren't having fun. If this is the case, then you might want to ask for some feedback and be very open minded and accepting of whatever they say - don't argue about it. It could be that you have created what you see as a wonderful involved plot using the character backstories but the players are seeing a railroad where the choices they want to make for their characters have no impact because the DM has already decided how the plot will progress.

I am not suggesting that this is actually the case but feedback from your players might help to resolve it. Involved storylines can be very cool but sometimes the DM has sort of implicitly decided how it will turn out whereas that really should be the choice of the player and character.

Alternatively, significant character involved storylines can sometimes leave one or more characters by the wayside while the plot focuses on someone else's story. If the group isn't fully invested in everyone's story then this can lead to the other players losing interest.

Anyway, at times it can be worthwhile not developing a completely detailed plot and story since the players may make an unexpected decision or take the plot in a different direction or as you have found out, some characters may drop out of the game for whatever reason so it can be advantageous to have a good plot but one that is not so involved with specific characters that it can't be adjusted.

It's always good to have a fallback if a session doesn't work out. We will often play board games in the case of cancellations.

Thanks to a lot of COVID-fueled progress, there are some good online board game options now. I personally like 7 Wonders on boardgamearena.

It can also be helpful to just fall back on an episodic campaign or modules for the time being. Something that requires a lot less effort on your part but still allows everyone to get together and play D&D. After the group gels a bit, you can reboot or just kind of segue into your planned campaign.

It happens. Try not to take it personally. The hardest part of any D&D campaign is the scheduling. Different people with different lives and different priorities make it extremely rare to run a full campaign without some recasting along the way. I've been playing D&D off and on since 1981 and literally every campaign I have ever been a part of ended with a different group of players than it started with. Sometimes just one or two, and the vast majority had seriously valid reasons for leaving, but that is just part of the game.

The toughest transition I have encountered (like most of us) was last spring when the covid lockdown halted our game. I had a really cool halfling gloom stalker who I was really enjoying, and I was just about to dip into a level of rogue to get some of that sweet sweet sneak attack, but then covid hit and the game ended. We all still kept in touch, and started playing again on Roll20 a few months later. But we started a whole new campaign from scratch with new characters. I would really like to have a chance someday to go back to that gloom stalker though. He was a lot of fun to play. 

So, don't sweat it. Just learn to adapt. It gets easier.