Debugging Orthanc

If you experience an error within Orthanc (or one of its plugins), that the troubleshooting sections (cf. here and here) do not help, and that you can’t provide a robust way to reproduce your issue by third-party developers, you’ll have to analyze the backtrace of Orthanc.

If you observe a fatal crash of Orthanc, where Orthanc stops abruptly (e.g. by creating a so-called “core dumped” or reporting an invalid memory access), which rarely occurs, please check the dedicated section). The present FAQ entry is rather about C++ exceptions that are thrown by Orthanc, typically as a consequence of invalid inputs, and that result in an error message reported by Orthanc (not in a crash), and for which the log files in verbose mode do not provide meaningful information.

Important reminder: Most issues with Orthanc can be solved by carefully looking at the Orthanc logs after starting Orthanc with the --verbose --trace-dicom command-line options!

Any system

First compile Orthanc by yourself, in debug mode by setting -DCMAKE_BUILD_TYPE=Debug when invoking CMake.

Then, learn how to use the debugger that is best suited to your platform (e.g. Microsoft Visual Studio, gdb, cgdb, or Xcode).

GNU/Linux system using gdb

The Orthanc project provides precompiled binaries with debug symbols for the mainline that can run on almost any recent GNU/Linux system (generated thanks to the LSB - Linux Standard Base SDK). This allows to debug Orthanc without compiling from sources. Here is a sample debug session to analyze an error that comes from an invalid configuration file:

$ wget
$ echo 'nope' > invalid.json
$ chmod +x ./Orthanc
$ gdb --args ./Orthanc invalid.json
(gdb) catch throw
Catchpoint 1 (throw)
(gdb) run
Starting program: /tmp/i/Orthanc invalid.json
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/".
W0103 18:25:01.540600             MAIN main.cpp:2041] Orthanc version: mainline (20240103T170440)
W0103 18:25:01.540636             MAIN main.cpp:1775] Performance warning: Non-release build, runtime debug assertions are turned on
W0103 18:25:01.540702             MAIN OrthancConfiguration.cpp:57] Reading the configuration from: "invalid.json"
E0103 18:25:01.540823             MAIN OrthancException.cpp:61] Cannot parse a JSON document: The configuration file does not follow the JSON syntax: invalid.json

Catchpoint 1 (exception thrown), 0x00007ffff7cae4a1 in __cxa_throw () from /lib/x86_64-linux-gnu/
(gdb) backtrace
#0  0x00007ffff7cae4a1 in __cxa_throw () from /lib/x86_64-linux-gnu/
#1  0x0000000000473745 in Orthanc::AddFileToConfiguration (target=..., path=...)
    at /home/jodogne/BuildBotWorker/Orthanc_mainline_-_LSB_Debug/build/OrthancServer/Sources/OrthancConfiguration.cpp:72
#2  0x0000000000473e98 in Orthanc::ReadConfiguration (target=..., configurationFile=0x7fffffffe302 "invalid.json")
    at /home/jodogne/BuildBotWorker/Orthanc_mainline_-_LSB_Debug/build/OrthancServer/Sources/OrthancConfiguration.cpp:149

If you are unable to analyze such a backtrace by yourself, feel free to post your backtrace on the Orthanc Users discussion forum. Do not forget to indicate the content of so that we can find the version of Orthanc that generated the core file.

If you want to read the source code of the backtrace, it is highly suggested to use cgdb with its set substitute-path command. First read the content of the revision.txt file to identify the revision of Orthanc. Then, you can type:

$ hg clone -r 723251b2b71e
$ cgdb --args ./Orthanc invalid.json
(gdb) set substitute-path /home/jodogne/BuildBotWorker/Orthanc_mainline_-_LSB_Debug/build/ ./orthanc/
(gdb) catch throw
(gdb) run
(gdb) frame 2


Besides the Orthanc core, debug LSB binaries are also available for most official plugins at the following location:

These binaries are identified as mainline-debug/.