"cannot start compilation: the output path is not specified for module..."

Walkthrough and resolution

At times, the IDE can be naughty and things which should be a cakewalk need a helping hand. So, here's an explicit guide so that your code sails through smoothly.

Ensuring project-wide consistency

Navigate to File > Project Structure > Project and set the Project compiler output field right. This preschool-level setting is the daycare for your compiled bytecode.

Making modules behave

If your stubborn modules are causing issues, turn on the inherit setting. This way, you have to set the path only once and your modules follow your Project compiler output like obedient minions.

Gradle specifics

For a Gradle project, navigate to the idea plugin in your build.gradle and align the output directories correctly, like so:

apply plugin: 'idea'

idea {
    module {
        inheritOutputDirs = false // turning off autoplay
        outputDir = file('path_to_main_classes') // where the big classes play
        testOutputDir = file('path_to_test_classes') // where the small classes play
    }
}
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Common pitfalls

Here are a few hot tips to avoid usual mistakes leading to the afore-noted error:

Harmony between IDE and build script

Ensure that the path specified in IntelliJ settings matches your build script expectations. If they’re not on the same page, both the developer and the IDE will be haunted with scary error messages.

Dot your "i"s and cross your "t"s on output paths

In the heat of the fixing spree, make sure you haven’t directed the path to a non-existent or inaccessible location. Naturally, that gives the IDE a mild heart attack.

Level up: Additional tips

Leveraging default paths

If setting custom paths seems like a battle, use the default output path IntelliJ provides. Quick win against potential path-related issues stirred up by custom configurations.

Invalidate and Initiate

Sometimes, IntelliJ clings to stale data, causing errors. Give it a fresh start by Invalidating caches and restarting the IDE.

Checkup on module dependencies

Inspect your module dependencies, incorrect or missing dependencies can sometimes dress up as output path issues. Navigate to Project Settings > Modules > Dependencies tab.