Error: "illegal reflective access operation has occurred"

[seishonagon]

I've installed version 0.6.1 on Mojave 10.14.6 using Homebrew, and I'm using it to git diff excel files.

Application excel_cmp works fine, except for a warning error:

WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access by org.apache.poi.util.DocumentHelper (file:/usr/local/Cellar/excel-compare/0.6.1/libexec/poi-ooxml-3.12.jar) to method com.sun.org.apache.xerces.internal.util.SecurityManager.setEntityExpansionLimit(int)
WARNING: Please consider reporting this to the maintainers of org.apache.poi.util.DocumentHelper
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release

It's not a big deal, but it makes the output that much harder to read ...

[xapple]

Just chiming in to report that this error is still present more than a year later.

[Svelix]

Yep, I also saw this just today.
The statement "All illegal access operations will be denied in a future release" makes me worried that this tool might stop working at some point, so I will not use consider it for our build-pipeline permanently.

[kiilivi]

This error occurs when using newer JDK than 8. I believe that this Apache POI library version is not compatible with JDK 17. JDK 11 still works.