unless one does; without doing
Attaches to the stem of a verb to express a necessary condition: 'unless you do X, ...'. The following clause often states a negative outcome or impossibility. The note 'with verb stem' indicates it follows the -masu stem form.
Unless you actually try it, you won't know whether you can do it.
Without studying more, passing will be difficult.
Similar conditional meaning, but なければ is a general conditional form that can attach to verbs, adjectives, and nouns, while ないことには is a fixed expression that specifically follows a verb stem and emphasizes a prerequisite action.
Also expresses 'if not', but ないと is more colloquial and can be used for warnings or obligations. ないことには is more formal and often used in logical or explanatory contexts.
Kanji spelling using 事; less common and may look stiff in modern writing.
Kanji spelling using 無い; rare and may be seen in older or formal texts.
Mixed kanji spelling; very rare and not recommended for learners.
A fixed expression combining the negative adjective ない, the nominalizer こと, and the particle には, literally 'in the case of not doing'. The construction grammaticalized into a conditional pattern meaning 'unless one does'.