How to Fix IntelliJ IDEA’s “Command-line is Too Long” Error for Spring Boot

Introduction

When you click the green Run button in IntelliJ IDEA to start a Spring Boot application, you may encounter the error “Command-line is too long”. This happens to many Java developers using modern frameworks.

Why does the command line become too long?

IntelliJ IDEA builds a standard java launch command that includes a -classpath argument containing the paths of all compiled classes and third‑party JARs. A typical command looks like:

# This is illustrative; actual paths are much longer
java -classpath "C:\path\to\dep1.jar;C:\path\to\dep2.jar;...;C:\path\to\your\classes" com.example.YourApplication

The -classpath parameter tells the JVM where to find .class files, including your compiled code and every dependency JAR (e.g., spring-boot-starter-web, mybatis-spring-boot-starter). Modern Spring Boot projects can have dozens or hundreds of dependencies, causing the classpath string to exceed the operating system’s maximum command‑line length (8191 characters on Windows). When this limit is breached, the OS rejects the command and the error appears.

How to solve it in one click

IntelliJ IDEA provides built‑in options to shorten the command line. Follow these steps:

Step 1: Open Run/Debug Configurations.

In the top‑right corner of IDEA, locate your application (e.g., QuickForumApplication) and choose Edit Configurations….

Step 2: Modify the “Shorten command line” option.

In the configuration window, find the “Shorten command line” setting. Its default value is often none, which leads to the error.

JAR manifest (recommended)

IDEA creates a temporary classpath.jar file and writes all dependency paths into its MANIFEST.MF. The JVM reads this manifest, resulting in a very short launch command.

@argfile (classpath file, also recommended)

IDEA creates a temporary text file containing the long classpath and launches the application with java @your_temp_file. The JVM reads the arguments from this file.

Step 3: Apply and run.

Select either JAR manifest or @argfile, click Apply and OK, then run the application again. The green Run button should now start the app without errors.

Permanent solution: modify the configuration template

To avoid repeating the steps for new projects, edit the IDEA configuration template:

Open Edit Configurations… again.

Click “Edit configuration templates…” in the lower‑left corner.

Select Spring Boot (or Application if not a Spring Boot project) from the left list.

Change the “Shorten command line” option to JAR manifest (or @argfile).

Save with OK.

From now on, every new Spring Boot run configuration will inherit this setting, preventing the “command line too long” problem.

Summary

Too many project dependencies make the -classpath argument exceed OS limits. In IntelliJ IDEA, change the “Shorten command line” option from none to JAR manifest or @argfile in the run configuration (or in the template) so the IDE uses a shorter, smarter way to pass the classpath to the JVM.

Hope this tutorial helps you focus on coding rather than environment configuration.