[jennie2486]

The error message that you got is only displayed if either the java binary or the .jar file in the plugin folder can't be found.

To check Java I run and receive:

java -version

C:\Program Files\Java\jre1.8.0_251\bin\java.exe

I also checked the JAVA_HOME path in terminal and received:

echo %JAVA_HOME%

C:\Progra~1\Java\jre1.8.0_251\bin\java.exe

But, just in case, I also specified the java binary path in the EpubCheck.json file. Still didn't work.

If it was a java or EpubCheck error, wouldn't I then have trouble running the plugin through terminal and Calibre, not to mention some of the other plugins that also rely on Java?

Calibre works fine, and displays all errors correctly, I've never had any issues at all with Calibre. Since I find myself using Sigil more often, I wanted to get EpubCheck and some other plugins working.

I run and receive on terminal the following:

java -jar  "C:\Users\jenni\AppData\Local\sigil-ebook\sigil\plugins\EpubCheck\epubcheck.jar"

At least one argument expected
EPUBCheck completed

I can also successfully check books using terminal, no problem:

 java -jar "C:\Users\jenni\OneDrive\Downloads\Sigil Plugins\EpubCheck\epubcheck.jar" "C:\Users\jenni\OneDrive\Documents\Books\Looking for Clara_ A Novel (6192)\Looking for Clara_ A Novel - Simona Grossi_epub3.epub"

Validating using EPUB version 3.2 rules.
ERROR(OPF-014): C:/Users/jenni/OneDrive/Documents/Books/books/Looking for Clara_ A Novel (6192)/Looking for Clara_ A Novel - Simona Grossi_epub3.epub/OEBPS/Section41.xhtml(-1,-1): The property "remote-resources" should be declared in the OPF file.
ERROR(RSC-006): C:/Users/jenni/OneDrive/Documents/Books/books/Looking for Clara_ A Novel (6192)/Looking for Clara_ A Novel - Simona Grossi_epub3.epub/OEBPS/Section41.xhtml(24,28): Remote resource reference not allowed; resource must be placed in the OCF.

Check finished with errors
Messages: 0 fatals / 2 errors / 0 warnings / 0 infos

EPUBCheck completed

This is so frustrating, only Sigil seems to have an issue.