Hey there, let's work through this annoying error you're hitting when setting up Tomcat 8.5 in Eclipse. This error typically pops up due to compatibility mismatches between your JRE version, Eclipse's Tomcat integration tools, or conflicting XML parsing libraries in your project. Here are the most reliable fixes to try:

1. 确认JRE版本兼容性 #

Tomcat 8.5 requires at least Java 7 (JRE 1.7) and works best with Java 8. Mismatched JRE versions are the most common cause of this error:

• Open Eclipse, go to Window > Preferences > Java > Installed JREs
• Ensure you have JRE 1.7+ (preferably 1.8) listed and set as the default
• Verify your Tomcat server uses this compatible JRE:
  • Open the Servers view via Window > Show View > Servers
  • Right-click your Tomcat 8.5 server > Properties
  • Under Server Locations, check the JRE dropdown selects the correct version

2. 更新Eclipse的Web Tools Platform (WTP)插件 #

Outdated WTP plugins often clash with newer Tomcat versions:

• Go to Help > Eclipse Marketplace
• Search for "Web Tools Platform"
• Install any available updates, then restart Eclipse
• Try reconfiguring your Tomcat server after the restart

3. 移除项目中冲突的XML解析Jar包 #

Third-party libraries like xercesImpl.jar or xml-apis.jar in your project's WEB-INF/lib can conflict with the JRE's built-in XML parsing classes:

• Navigate to your project's WEB-INF/lib directory
• Look for any XML-related jars that duplicate JRE functionality
• Remove these jars (or mark them as "provided" if they're only needed for build time)
• Clean and rebuild your project, then attempt to start the Tomcat server again

4. 重置Tomcat服务器配置 #

Corrupted Eclipse server config files can also trigger this error:

• In the Servers view, right-click your Tomcat 8.5 server > Delete (this only removes the Eclipse config, not your actual Tomcat installation)
• Re-add the server by clicking the No servers are available... link in the Servers view
• Follow the setup wizard, double-checking you select the correct JRE and Tomcat installation path

If you still run into issues after these steps, check Eclipse's error log for more details: Window > Show View > Other > General > Error Log. The full stack trace there will help pinpoint the exact conflict source.

内容的提问来源于stack exchange，提问作者pavan kumar