Hello Dear 3D printing People.
If you are in this hobby for a while, You've probably got your fair share of failed prints. Usually failing for no apparent reason, ruining your 24 hour print...

I've been pretty lucky with my MSLA printer for the first year I was using it. Almost no problems at all. Good things never last forever though, and lately I am getting more issues like poor surface finish on my parts or prints not sticking to the build plate etc.
That means that I spend a lot of time searching for solutions to different printing issues online. I've found a lot of online troubleshooting guides that helped me fixing most of my problems and I thought it may be a good idea to share some of those resources with you.
Below you can find a list of links together with short commentaries. I hope this is useful and may save you some headache.
MSLA/LCD - Guides
Elegoo Mars/Pro troubleshooting guide
3dprinterly.com
8 Ways How to Fix Resin 3D Prints That Fails Halfway
3dprinterly.com
Some of the videos are related to a particular brand of printers, but there are more general tips available there as well.
l3d.ie
Tips for prints that wont print at all + links to a few different problems and solutions.
technipages.com
A few common problems explained
3dprintingrealms.com
5 Settings to Improve Your SLA/DLP/LCD 3D Print Quality
instructables.com
Elegoo Mars and Saturn troubleshooting forum
elegoomars.com
Phrozen help center
phrozen3d.com
MSLA/LCD - Videos
Why Resin 3D Prints Fail - Improve Your Prints - Tips on Understanding Overhangs and Supports
Nerdtronic - You Tube
My 3D Print Failed, Now What? Anycubic SLA
Spikey Bits - You Tube
Top Ten Reasons Why Resin Prints Fail
Michael Makes Everything - You Tube
3D Resin Printing 101 - Why Prints Fail
Random Making Encounters - You Tube
3d RESIN PRINT FAILURES and SOLUTIONS not sticking to build plate sticking to fep, exposure settings
FacilityD20 - You Tube
Stop Resin 3D Print Fails! Bed Adhesion Tips & Tricks
Uncle Jessy - You Tube
RESIN FAILS: What causes partial support fails and how to fix it.
Hiro Creations - You Tube
UN-STUCK your 3D Prints, and keep prints from sticking. (REAL QUICK)
TheCrafsMan SteadyCraftin - You Tube
Below you I've included some links for FDM/FFF printing problems. There are more resources available for 'spaghetti' printers, that is probably because of technology being available longer. It's been some time since I was printing with my Prusa I3, but I still have nightmares about it. My deepest sympathy ;)
FDM/FFF Guides
Prusa Knowledge Base
prusa3d.com
44 problems ultimate guide
rigid.ink
41 problems with detailed explanation
all3dp.com
27 problems/solutions - very well explained
simplify3d.com
22 issues with good pictures
cults3d.com
19 common printing problems
geeetech.com
14 problems with possible causes and solutions
ninjatek.com
Comprehensive guide with videos and pictures.
apm-designs.com
More examples with illustrations and videos.
bitfab.io
A few common problems with pictures.
3dk.berlin
FDM/FFF - Videos
Troubleshooting 3D Printer Issues
Breaks'n'Makes - You Tube
3D Printing Basics: When things go wrong! (Ep9)
Thomas Sanlander - You Tube
3D printing First Layer issues troubleshooting Guide
The First Layer - You Tube
5 3D Printing Mistakes you WILL make - and how to avoid them! 3D Printing 101
Maker's Muse - You Tube
3D Printing 101: Troubleshooting a Bad Print / Installing a New Nozzle
3D Printing Nerd - You Tube
How a 3DBenchy can tell where your 3D prints need improvement
Teaching Tech - You Tube
3D Printer Troubleshooting Guide: Clogged Nozzles
MatterHackers - YouTube
That's it for now. If you have any good resources that aren't on the list, please share them. Lets exchange some wisdom :)