Quick Answer
The correct answer is ModuleNotFoundException, which is thrown at startup when a required module is missing from the module path in Java 17. This occurs during the resolution phase of the Java Platform Module System (JPMS), where the module graph is built and validated; if a module declared in a `requires` clause cannot be located on the module path, the system immediately fails with this exception rather than attempting to run the application. On the Oracle Certified Professional Java SE 17 Developer 1Z0-829 exam, this question tests your understanding of JPMS startup behavior and common deployment pitfalls—a frequent trap is confusing this with `ClassNotFoundException` or `NoClassDefFoundError`, which occur at runtime, not during module resolution. Remember that module path issues are caught early, before any code executes. A useful memory tip: think "Module path = ModuleNotFound; Class path = ClassNotFound"—the exception name directly mirrors the missing element.
This 1Z0-829 practice question tests your understanding of java platform overview and packaging. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A Java 17 application is deployed on a server. The application uses modules but one required module is missing from the module path. Which exception will be thrown at startup?
ExceptionInInitializerError
Why wrong: This occurs during static initialization.
NoClassDefFoundError
Why wrong: This occurs when a class is missing at runtime, not a module.
ClassNotFoundException
Why wrong: This is for class loading, not module resolution.
ModuleNotFoundException
Thrown when a required module cannot be resolved.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
ModuleNotFoundException
Option D is correct because when a required module is missing from the module path in Java 17, the module system throws `ModuleNotFoundException` during the resolution phase at startup. This exception is specific to the Java Platform Module System (JPMS) and indicates that a module declared in `requires` clauses cannot be located.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
ExceptionInInitializerError
Why it's wrong here
This occurs during static initialization.
NoClassDefFoundError
Why it's wrong here
This occurs when a class is missing at runtime, not a module.
ClassNotFoundException
Why it's wrong here
This is for class loading, not module resolution.
ModuleNotFoundException
Why this is correct
Thrown when a required module cannot be resolved.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
The trap here is that candidates confuse module-level errors with class-level errors, mistakenly choosing `NoClassDefFoundError` or `ClassNotFoundException` because they think of missing JARs on the classpath, but the exam specifically tests the JPMS behavior where `ModuleNotFoundException` is the correct exception for a missing module on the module path.
Detailed technical explanation
The JPMS module resolution occurs at startup before any application code runs; the module system reads `module-info.class` files and resolves `requires` directives. If a required module is absent from the module path, the resolver throws `ModuleNotFoundException` as part of the `LayerInstantiationException` chain. In real-world scenarios, this often happens when a library's automatic module name does not match the expected module name in `module-info.java`, or when a module is accidentally omitted from the `--add-modules` JVM argument.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
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FAQ
Java Platform Overview and Packaging — This question tests Java Platform Overview and Packaging — Read the scenario before looking for a memorised answer..
The correct answer is: ModuleNotFoundException — Option D is correct because when a required module is missing from the module path in Java 17, the module system throws `ModuleNotFoundException` during the resolution phase at startup. This exception is specific to the Java Platform Module System (JPMS) and indicates that a module declared in `requires` clauses cannot be located.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Same concept, more angles
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Variation 1. A developer receives the above error when running a modular Java application. What is the most likely cause?
mediumWhy B: When a modular Java application throws an error indicating that a module cannot be found, the most common cause is that the module's JAR or directory is not present on the module path. The module path is specified using the `--module-path` option (or `-p`) when launching the application with `java --module`. If `com.example.app` is not on that path, the module system cannot resolve it, leading to a `ModuleNotFoundException` or similar error.
Last reviewed: Jun 11, 2026
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