1. Open the following path under your workspace folder:
***\.metadata\.plugins\org.eclipse.core.resources
Then delete the .snap file. I have this .snap file when eclipse is open, but when I close eclipse and look at this folder, I find that the .snap file is gone, so this method is not used successfully. It is said that some people use it on the Internet. It worked. You can try it.
2. Open the following path under your workspace folder:
***\.metadata\.plugins\org.eclipse.wst.server.core
Delete the temp* folder in it. I have temp0 and temp1. It may be a tomcat corresponding to a temp. It is not clear. After deleting it, restart eclipse, and tomcat can be used.