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  1. julian
  2. PLCnext Engineer
  3. Monday, 28 December 2020


I was working with an AXC F 2152 with FW2020.6 and Smart Elements and PLCnext Engineer 2020.6.2.

I updated to the new soft 2021.0.1 and FW 2021.0.0 LTS in the AXC

Then the AXC goes to FAIL (red led lights fix) and the soft gives me the error I send to you.

Error writing

If I come back to the former version of FW2020.6, everything goes well with software 2021.0.0 LTS

Do you have news about a similar problem with the firmware update ?


Thanks for your help.

Best regards.



peterdallmann Accepted Answer Pending Moderation

Hi Julian,

I have seen the same issue yesterday.

The running project was with FW 2020.6 and Engineer version 2020.6.1 no problems there. Well, accept the slow VPN communication. What was the reason for the update.

I was running the FW update to version to FW 2021.LTS. After that I did a factory reset of the controller. In the time that went on, I did modify my project to the firmware template 2021.LTS.

Before downloading the project, I corrected the user admin in the WbM.

That all done, I downloaded the project to the controller. Well, got the same error as you did. Controller goes in to FAIL mode with no real information. Could not even get the logs from the controller.

So, I did restart the controller and now I have the D - LED on and nothing else. I can ping the controller but can't access anything. So I guess that I have now a new paperweight for my desk.

Since this is an running application at a client, my only option was to change the controller to a new one with FW 2020.6. Download my program and look - its running.


I know we are in difficult times and you guy's from Phoeninx are doing what you can. But this isn't helping us. You wish that we keep the firmware up-to-date, especially this version with the fix for the VPN communication. So please make sure that you don't kill our running applications.

This application has been running un-modified from firmware 2020.LTS and all in between up to FW 2020.6.


To end on a high note: I did have a controller in the office where I udated the FW to 2021.LTS for testing the VPN performance. There the update was going well. But there I have programmed the controller from scratch - a complete new project.

So Phoenix,let us know when you have come up with an explaination and a fix.


Peter Paul

Frank PLCnext Team Accepted Answer Pending Moderation

Hi Julian, Peter,

first of all I hope that you've had pleasant start into the new year!

As second I've to apologize that you both ha directly issues during the update to the brand new 2021.0.

Of course we've spend a lot of time and effort to ensure that the firmware is compatible to the older versions, but as usual with such complex systems there might be gaps which we did not encounter.
It seem that you both found there a flaw!

Now it is for us most important to find the cause to help you and the community as soon as even possible.

I'm already in contact with Peter and @Julian I would come also directly back to you that we can have a closer look into your application as well.

I'll keep this post also for all the others open and will update it when there are some more details available.

Take care,


Phoenix Contact Electronics Headquarter - PLCnext Runtime Product Management and Support

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