Most people who fail the JLPT were not far off. They lost it to something on this list.
1. Ignoring the sectional minimum
The most common fatal error.
You must clear the overall pass mark and a minimum in every scoring section — 19 of 60, or 38 of 120 for the combined section at N4 and N5. A candidate at N3 scoring 58, 58 and 18 totals 134, well above the 95 pass mark, and fails.
Candidates who track only their total in practice have no idea this is coming. Score every mock by section. See JLPT passing scores.
2. Leaving listening until the end
Listening is a processing speed. It improves over months, through daily exposure, and it cannot be compressed.
It is also the easiest section to defer, because week-to-week progress is invisible. So it gets postponed, and it is the section most likely to be the one under 19.
Twenty minutes daily, from the first week, regardless of level. See JLPT listening strategy.
3. Not finishing the reading section
At N2 and N1 especially, a large share of reading failures are unattempted questions rather than wrong ones.
This is a pacing problem, not a comprehension problem, and it responds to timed practice rather than to more vocabulary. Candidates who practise reading untimed have not practised the exam. See JLPT reading strategy.
4. Registering for the wrong level
You register for one level, you cannot change it, and a fail costs six months because the test runs twice a year.
Optimistic registration is expensive. Sit a full timed past paper at the level you are considering before the registration deadline, and register for the level you can actually pass.
5. Leaving answers blank
There is no negative marking. A blank and a wrong answer score identically, so a guess is strictly free.
Fill in every bubble before time is called, even at random. Every year, people lose passes to empty rows.
6. Mis-shading the answer sheet
It is machine-read. Answers shifted by one row — which happens when you skip a question in the booklet but not on the sheet — can destroy an entire section.
Check your row number at each page turn. Bring more than one HB pencil and a proper eraser.
7. Studying grammar instead of vocabulary
Grammar feels like studying. From N3 upwards, vocabulary is the bottleneck — the grammar syllabus for a level fits in one book, the vocabulary takes a year.
Candidates who spend a year on grammar points and neglect daily vocabulary arrive knowing a great deal about a language they cannot read fast enough.
8. Misdiagnosing wrong answers
When you get a practice question wrong, it was one of four things: an unknown word, a misread structure, running out of time, or carelessness.
Four causes, four completely different fixes — and most candidates label all four as “I need to study more”. A timing failure does not respond to vocabulary.
9. Stopping between sittings
Two months of nothing after a test is the standard pattern, and it means the retake starts from a worse position than the last one finished at.
Twenty minutes of listening and a vocabulary review. It costs nothing and protects everything.
10. Chasing a level you do not need
If your goal is a Specified Skilled Worker visa, the requirement is N4 or JFT-Basic at 200+. Preparing for N2 first delays your arrival by two years and adds nothing to the application.
Get to Japan, then build the level — the language is far easier to acquire there. See JFT-Basic or JLPT.