No output in Custom.log after upgrading Simulation to FW2026.0.2

PLCnext Technology & PLCnext Controls
1

I recently upgraded to the new version of the simulation, from 2025 to 2026 for AXC F 1152.
I noticed that there’s no output written to Custom.log in /opt/plcnext/logs/

The output used to be like this:

09.06.26 10:24:39.432 MyCustomComponent INFO - Asio version: 103600
09.06.26 10:24:40.102 MyCustomComponent INFO - void MyCustom::MyCustomComponent::OnPlcLoaded()
09.06.26 10:24:44.730 MyCustomComponent INFO - void MyCustom::MyCustomComponent::OnPlcStarted()
09.06.26 10:24:44.747 MyCustomComponent INFO - void MyCustom::MyCustomComponent::AsioWorker()
09.06.26 10:24:44.773 MyCustomComponent INFO - void MyCustom::MyCustomComponent::AsioWorker()
09.06.26 10:24:44.781 MyCustomComponent INFO - refreshing endpoint 10.0.21.1: 54321

Now the file still exists, but it’s completely empty.
Did I miss a step, didn’t see anything in the Toolchain notes?

What can I do next?

2

At the moment we are unable to reproduce this behavior on our side.

Would it be possible for you to share a minimal example project where this issue occurs? That would help us investigate this further.

3

I’m guessing you’d want to see the C++ code for the program/component?
I don’t think a PLCnext Engineer project with the resulting binaries will be helpful in your investigation?

4

Building with PLCnext CLI 2026.0.0 didn’t help.

5

If you could post one or more C++ code snippets showing how the logging is being done, that could help to reproduce and diagnose the problem.

If you are using the static Log class, then the class must be explicitly initialised:

image
image1252×339 19.2 KB

(source: Changes: Miscellaneous )

On the other hand, if you are using the Loggable<> template then initialisation is not required and the messages should appear in the Custom.log file.

6

I did find my logging, it’s logged to /opt/plcnext/log/Arp.log now.
Unsure if it was always there, think it was only in Custom.log before.

16.06.26 08:41:42.962 Arp INFO - Build date: Jun 16 2026
16.06.26 08:41:42.963 Arp INFO - Build time: 08:27:29
16.06.26 08:41:42.963 Arp INFO - Build compiler: 13.4.0
16.06.26 08:41:42.964 Arp INFO - C++ standard version: 202002
16.06.26 08:41:42.964 Arp INFO - ARP Version: 2026.0.3 LTS
16.06.26 08:41:42.964 Arp INFO - ARP ABI version: 2.1
16.06.26 08:41:42.964 Arp INFO - Asio version: 103600

Logging code is not very straight forward, I have some ABI-version defines in the code to stay compatible with both ABIs and I also added an abstraction to activate a custom logger when unit testing the code.
I can understand those getting in the way, I’ll take another look at the linked docs, to see if I made a mistake somewhere, I’ll try to bring it down to a MVP.