# How to debug my Crystal app? **URL:** \ **Category:** Help & Support\ **Created:** [June 16, 2021, 3:53pm UTC](https://forum.crystal-lang.org/t/how-to-debug-my-crystal-app/3393 "2021-06-16T15:53:03Z")\ **Posts on this page:** 14\ **Page:** 1
**Author:** ![gummybears](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.crystal-lang.org/gummybears/32/1886_2.png) [@gummybears](https://forum.crystal-lang.org/u/gummybears)\ **Post date:** [June 16, 2021, 3:53pm UTC](https://forum.crystal-lang.org/t/how-to-debug-my-crystal-app/3393/1 "2021-06-16T15:53:03Z")
I read the topic Debugger support but could not find a small example or a link to doc’s on how to debug a Crystal app. ---
**Author:** ![asterite](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.crystal-lang.org/asterite/32/60_2.png) [@asterite](https://forum.crystal-lang.org/u/asterite)\ **Post date:** [June 16, 2021, 4:04pm UTC](https://forum.crystal-lang.org/t/how-to-debug-my-crystal-app/3393/2 "2021-06-16T16:04:16Z")
No nice way to do it right now ---
**Author:** ![bcardiff](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.crystal-lang.org/bcardiff/32/3_2.png) [@bcardiff](https://forum.crystal-lang.org/u/bcardiff)\ **Post date:** [June 16, 2021, 4:51pm UTC](https://forum.crystal-lang.org/t/how-to-debug-my-crystal-app/3393/3 "2021-06-16T16:51:23Z")
I wrote this guide for the support within vscode [Debug Crystal in VSCode via CodeLLDB - DEV Community](https://dev.to/bcardiff/debug-crystal-in-vscode-via-codelldb-3lf) If you know gdb lldb you can use them, yet there is a limitation regarding what values can be inspected. ---
**Author:** ![gummybears](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.crystal-lang.org/gummybears/32/1886_2.png) [@gummybears](https://forum.crystal-lang.org/u/gummybears)\ **Post date:** [June 17, 2021, 3:12pm UTC](https://forum.crystal-lang.org/t/how-to-debug-my-crystal-app/3393/4 "2021-06-17T15:12:54Z")
Perhaps time for me to switch from Geany to VSCode. Thanks. ---
**Author:** ![rogerdpack](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.crystal-lang.org/rogerdpack/32/117_2.png) [@rogerdpack](https://forum.crystal-lang.org/u/rogerdpack)\ **Post date:** [June 23, 2021, 6:11pm UTC](https://forum.crystal-lang.org/t/how-to-debug-my-crystal-app/3393/5 "2021-06-23T18:11:20Z")
You can kind of use gdb the “normal way” as it were… ---
**Author:** ![stellarpower](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.crystal-lang.org/stellarpower/32/2072_2.png) [@stellarpower](https://forum.crystal-lang.org/u/stellarpower)\ **Post date:** [June 2, 2024, 2:10pm UTC](https://forum.crystal-lang.org/t/how-to-debug-my-crystal-app/3393/6 "2024-06-02T14:10:19Z")
@bcardiff Do you know if the LLDB helpers are up-to-date at all? I still see Strings formatted as an initial character and a length and I’m on LLDB version 15. Thanks ---
**Author:** ![nobodywasishere](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.crystal-lang.org/nobodywasishere/32/1983_2.png) [@nobodywasishere](https://forum.crystal-lang.org/u/nobodywasishere)\ **Post date:** [June 2, 2024, 3:03pm UTC](https://forum.crystal-lang.org/t/how-to-debug-my-crystal-app/3393/7 "2024-06-02T15:03:21Z")
That is normal unfortunately, and something I’m currently looking into ---
**Author:** ![Blacksmoke16](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.crystal-lang.org/blacksmoke16/32/1241_2.png) [@Blacksmoke16](https://forum.crystal-lang.org/u/Blacksmoke16)\ **Post date:** [June 2, 2024, 3:29pm UTC](https://forum.crystal-lang.org/t/how-to-debug-my-crystal-app/3393/8 "2024-06-02T15:29:38Z")
Possibly related: [LLVM 16 supports Crystal's DWARF5 language code · Issue #13174 · crystal-lang/crystal · GitHub](https://github.com/crystal-lang/crystal/issues/13174) ---
**Author:** ![stellarpower](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.crystal-lang.org/stellarpower/32/2072_2.png) [@stellarpower](https://forum.crystal-lang.org/u/stellarpower)\ **Post date:** [June 2, 2024, 5:37pm UTC](https://forum.crystal-lang.org/t/how-to-debug-my-crystal-app/3393/9 "2024-06-02T17:37:41Z")
Ah, yes, good point. I have had problems with DWARF 4/5 with gdb when compiling with clang, but in those situations I have had some output telling me gdb can’t make sense of them. I tried lldb-17 with the same result though. ---
**Author:** ![zw963](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.crystal-lang.org/zw963/32/1623_2.png) [@zw963](https://forum.crystal-lang.org/u/zw963)\ **Post date:** [June 3, 2024, 5:42am UTC](https://forum.crystal-lang.org/t/how-to-debug-my-crystal-app/3393/10 "2024-06-03T05:42:50Z")
Does this solution still available? i test on my emacs with dap-codelldb 1.8.1, get following error: ```auto plugins/dap-mode/.extension/vscode/codelldb/extension/adapter/codelldb --port 12489 [ERROR codelldb::dap_session] Deserialization error: data did not match any variant of untagged enum ResponseResult at line 1 column 84 [ERROR codelldb::terminal] [61] channel closed ``` ---
**Author:** ![bcardiff](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.crystal-lang.org/bcardiff/32/3_2.png) [@bcardiff](https://forum.crystal-lang.org/u/bcardiff)\ **Post date:** [June 4, 2024, 1:05pm UTC](https://forum.crystal-lang.org/t/how-to-debug-my-crystal-app/3393/11 "2024-06-04T13:05:50Z")
I just run the things as described in [Debug Crystal in VSCode via CodeLLDB - DEV Community](https://dev.to/bcardiff/debug-crystal-in-vscode-via-codelldb-3lf) and things works as expected using CodeLLDB vscode extension. I also just try using lldb from mac directly and it seems to work. The script is mimicking what ./spec/debug/driver.cr do under the hood. ```auto % crystal build --debug ./spec/debug/strings.cr -o string-debug % lldb string-debug (lldb) target create "string-debug" Current executable set to '/Users/bcardiff/Projects/crystal/master/string-debug' (arm64). (lldb) version lldb-1500.0.200.58 Apple Swift version 5.9.2 (swiftlang-5.9.2.2.56 clang-1500.1.0.2.5) (lldb) command script import etc/lldb/crystal_formatters.py (lldb) breakpoint set -n main -G true -o true -C 'process handle -s false -n false SIGSEGV SIGBUS' Breakpoint 1: 2 locations. (lldb) breakpoint set -n __crystal_main -G true -o true -C 'process handle -s true -n true SIGSEGV SIGBUS' Breakpoint 2: where = string-debug`__crystal_main + 208 at strings.cr:1:1, address = 0x000000010000394c (lldb) run Process 36134 launched: '/Users/bcardiff/Projects/crystal/master/string-debug' (arm64) (lldb) process handle -s false -n false SIGSEGV SIGBUS NAME PASS STOP NOTIFY =========== ===== ===== ====== SIGSEGV true false false SIGBUS true false false (lldb) process handle -s true -n true SIGSEGV SIGBUS NAME PASS STOP NOTIFY =========== ===== ===== ====== SIGSEGV true true true SIGBUS true true true Process 36134 stopped * thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BREAKPOINT (code=1, subcode=0x100003c8c) frame #0: 0x0000000100003c90 string-debug`__crystal_main at strings.cr:9:1 6 # print: b 7 # lldb-check: (String *) $1 = {{0x[0-9a-f]+}} "abcσdeσf" 8 # gdb-check: $2 = "abcσdeσf" -> 9 debugger Target 0: (string-debug) stopped. (lldb) print a (String *) 0x00000001000c5970 "hello world" (lldb) print b (String *) 0x00000001000c5990 "abcσdeσf" ``` ---
**Author:** ![zw963](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.crystal-lang.org/zw963/32/1623_2.png) [@zw963](https://forum.crystal-lang.org/u/zw963)\ **Post date:** [June 4, 2024, 1:20pm UTC](https://forum.crystal-lang.org/t/how-to-debug-my-crystal-app/3393/12 "2024-06-04T13:20:21Z")
> [@bcardiff](#): > > `command script import etc/lldb/crystal_formatters.py` Hi, I get following error on my my arch linux when try to reproduce your’s process. ```auto ╰─ $ lldb string-debug (lldb) target create "string-debug" Current executable set to '/home/zw963/Crystal/crystal-lang/crystal/string-debug' (x86_64). (lldb) command script import etc/lldb/crystal_formatters.py /home/zw963/Crystal/crystal-lang/crystal/etc/lldb/crystal_formatters.py:60: SyntaxWarning: invalid escape sequence '\(' debugger.HandleCommand('type synthetic add -l crystal_formatters.CrystalArraySyntheticProvider -x "^Array\(.+\)(\s*\**)?" -w Crystal') /home/zw963/Crystal/crystal-lang/crystal/etc/lldb/crystal_formatters.py:61: SyntaxWarning: invalid escape sequence '\(' debugger.HandleCommand('type summary add -F crystal_formatters.CrystalString_SummaryProvider -x "^(String|\(String \| Nil\))(\s*\**)?$" -w Crystal') (lldb) ``` ---
**Author:** ![bcardiff](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.crystal-lang.org/bcardiff/32/3_2.png) [@bcardiff](https://forum.crystal-lang.org/u/bcardiff)\ **Post date:** [June 4, 2024, 6:47pm UTC](https://forum.crystal-lang.org/t/how-to-debug-my-crystal-app/3393/13 "2024-06-04T18:47:56Z")
I’m not sure, maybe is a python issue. If you copy/edit `crystal_formatters.py`, can you check if adding `r` to the following strings fix the issue? I didn’t try but a couple of search points into that direction. Disclaimer: I’m not familiar with python. ```auto def __lldb_init_module(debugger, dict): debugger.HandleCommand(r'type synthetic add -l crystal_formatters.CrystalArraySyntheticProvider -x "^Array\(.+\)(\s*\**)?" -w Crystal') debugger.HandleCommand(r'type summary add -F crystal_formatters.CrystalString_SummaryProvider -x "^(String|\(String \| Nil\))(\s*\**)?$" -w Crystal') debugger.HandleCommand(r'type category enable Crystal') ``` ---
**Author:** ![zw963](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.crystal-lang.org/zw963/32/1623_2.png) [@zw963](https://forum.crystal-lang.org/u/zw963)\ **Post date:** [June 5, 2024, 2:38am UTC](https://forum.crystal-lang.org/t/how-to-debug-my-crystal-app/3393/14 "2024-06-05T02:38:28Z")
> [@bcardiff](#): > > can you check if > adding `r` to the following strings fix the issue? It is working! thank you very much.