Java 21: Could not find agent library instrument on the library path

Today I was trying to load a -javaagent on Java 21 / ColdFusion 2025 on Windows Server 2022, but I was getting the following error:

Error occurred during initialization of VM Could not find agent library instrument on the library path, with error: Can't find dependent libraries Module java.instrument may be missing from runtime image.

Let's take a step back because I was actually not finding any error messages, there was nothing in ColdFusion's Log directory. The only error logged was in Event Viewer, was a quite unhelpful:

The ColdFusion 2025 Application Server service terminated with the following service-specific error: The system cannot find the file specified.

I was only able to see that above error if I tried running:

coldfusion.exe -start -console

Now with that error, the first thing I did was make sure that the java.instrument module was actually part of the JVM I was using. It is possible to ship a JVM without certain modules using JLink, so I wanted to see if Adobe had done that with ColdFusion 2025.

java.exe --list-modules

And it does in fact list:

java.instrument@21.0.6

Next I am checking to see if instrument.dll indeed in the JVM folder, and it was.

Next I invoked the java agent using java.exe directly instead of via coldfusion.exe, and it worked fine. So it did not appear to be an issue with the JVM, or the JavaAgent itself. This leaves coldfusion.exe, which invokes the JVM a little differently than java.exe, I believe it is using jvm.dll.

The error message does appear to indicate that it cannot find the instrument.dll, I tried adding the jvm bin directory to the java.library.path, but that still didn't work. Finally adding the JVM bin directory to the system PATH environment variable did the trick, and Java was now able to find the instrument.dll library.

I put the following in a bat file to test it first:

set PATH=C:\java\jdk-21.0.6\bin;C:\java\jdk-21.0.6\bin\server;%PATH%

Then after finally adding it to the system environment variables I was able to start the ColdFusion 2025 Application Server Service.

Note: The ColdFusion service actually executes coldfusionsvc.exe, which then creates a sub process of coldfusion.exe

I'm not sure if this is a common issue, or if I did something to cause this on the server (I was a test server that I was tinkering around on quite a bit), but I figured I would post it, incase it helps anyone else.