Here is a thread to showcase 3D print issues and their solutions (does not include software/firmware issues unless they directly affected a printed object). Note: some symptoms can have several different underlying problems with different solutions for each, so use this as a guide of what possibilities to look into on your prints.
For those posting your experiences, please include a photo(s) of the problem, a description of both the problem and its solution for the specific case you are posting, and any other details relevant to such.
1) Symptom: Inconsistent initial layer lines
Problem: Nozzle plowing/too low
Solution: Raise z-offset and/or recalibrate bed level
2) Symptom: Line & layer adhesion failure/separation during printing
Problem: Under-extrusion from excessive tension on filament
Solution: Find source of tension and relieve
3) Symptom: Repeating pattern on exterior surface
Problem: Infill showing through walls
Solution: Adjust slicer settings (walls before infill, wall printing order, outer wall before inner wall, etc.)
4) Symptom: specific spot initial layer adhesion failure
Problem: Dirty build plate
Solution: Clean build plate
5) Symptom: Filament dribble during travel moves and lines after travel moves not connecting
Problem: Nozzle oozing during travel moves
Solution: Adjust slicer setting Combing mode from “All” to “Within Infill”
