JDTLS keeps crashing but not able to figure out why

[steinarb]

Platform emacs 30.1, debian 13.4 "trixie", amd64, lsp-mode 20260424.1524 (melpa)

Need help debugging JDTLS crashes.

JDTLS keeps crashing for me with the following error messages in the minibuffer

LSP :: jdtls has exited (exited abnormally with code 13)
Server jdtls:155652/starting exited (check corresponding stderr buffer for details). Do you want to restart it? (y or n) n

When I check the stderr buffer as suggested, all the stderr buffer contains is:

Process jdtls stderr finished

The FAQ How do I troubleshoot "Server FOO-LS:pid exited with status signal. Do you want to restart it? (y or n)"? says to then check the *lsp-log*buffer, but there isn't much of interest their either: https://gist.github.com/steinarb/d2f12c882d21d712beacfd6d95920a07
(or rather: nothing in lsp-log tells my anything I'm able to make use of to debug this)

My .emacs setup for lsp-mode for java combined with treesitter for java is here:

(when (treesit-language-available-p 'java)
  (add-to-list 'major-mode-remap-alist '(java-mode . java-ts-mode))
  (when (require 'lsp-java nil t)
    (setopt lsp-java-format-enabled nil)
    (add-hook 'java-ts-mode-hook #'lsp))
  (when (require 'lsp-java-boot nil t)
    (add-hook 'lsp-mode-hook #'lsp-lens-mode)
    (add-hook 'java-ts-mode-hook #'lsp-java-boot-lens-mode)))

More information: I visit a lot of java projects in different workspaces, some of which are quite large (local clones of various open source projects) and I think my setup uses only a single workspace in JDT.LS..? So maybe the workspace has gotten too large for JDTLS...? (just guessing here...)

Thanks!

• Steinar

[steinarb]

I did this today:

1. Stopped all emacs instances
2. Added the following to my ~/.emacs (I want JDTLS for maven multi module java projects and I use already use projectile, not sure how much effect excluding the eclipse directories and files have, but they weren't already in the list, so... every little helps...)

   ;; Add some eclipse generated files and directories to lsp-mode's list of ignored files
   (with-eval-after-load 'lsp-mode
     (add-to-list 'lsp-file-watch-ignored-directories "[/\\\\]\\.project$")
     (add-to-list 'lsp-file-watch-ignored-directories "[/\\\\]\\.classpath$")
     (add-to-list 'lsp-file-watch-ignored-directories "[/\\\\]\\.settings$"))
   
   ;; Adapt lsp-mode to the projects I want lsp-mode for (i.e. maven java projects (most are multi-module maven projects) all handled by projectile)
   (setopt lsp-auto-guess-root t ; use projectile to guess project roots
           lsp-java-import-maven-enabled t ; same as default, but left in to make clear we're dealing with maven projects
           lsp-java-configuration-maven-user-settings nil) ; also same as default, left in for the same reason
   

3. Deleted the existing JDTLS

   rm -rf ~/.emacs.d/.cache/lsp/eclipse.jdt.ls/
   

4. Started a fresh emacs and tried installing JDTLS with M-x lsp-install-server but JDTLS install didn't happen, ~/.emacs.d/.cache/lsp/stayed empty
5. Googled a little and what I found made me delete ~/.emacs.d/.lsp-session-v1
6. After deletion of .lsp-session-v1 JDTLS installation continued on its own without needing any intervention from me

Back up and things seems to be working. At least JDTLS isn't crashing for me all the time now, with just a single eclipse workspace imported.

Time will show how JDTLS and lsp-mode handles getting more eclipse workspaces in the list (most of my projects are maven multi module java projects, where the top pom directory also serves as an eclipse workspace).