'Unknown exception' errormessage while using append in exportgraphics

Hi, can anyone tell me why I get the error 'Unknown exeption' when I use 'append' in the exportgraphics function. Because when I use exportgraphics without 'append' it works. If it should not go in such a way, I would be glad around alternativen.

Thats the code (nothing special):

        Fig= figure(1);
        set(gcf,'Units','Normalized','OuterPosition',[0 0 1 1]);
        subplot(4,1,1);
        plot(tmp_zeit(valueSlotF2),tmp_APP_r(valueSlotF2),'LineWidth',2,'Color','#0072BD');
        ylabel('APP_r','Interpreter','none');xlabel('Zeit [s]');title(Name(i),'Interpreter','none');
        
        set(gcf,'Renderer','painters');
        set(gcf,'PaperOrientation','landscape','PaperPositionMode','manual','PaperPosition',[-1.5 0 40 21.00]);
        exportgraphics(gcf,strcat(path,Filename,'.pdf'),'Append',true);

Please do not wonder why there is only one of 4 subplots to see, I have not inserted the others here, because it is exactly the same 4 times.

And the variables path and filename I have also not inserted are also uninteresting for the problem.

Thanks for the help!

[Bala Tripura Bodapati]

Hi Lukas

I am not able to reproduce the issue at my end. On creating a sample plot with your provided code as reference, I have used the 'Append' property and it worked fine in MATLAB R2021b.

Could you share the following information which helps me reproduce and debug the issue at my end:

1. The Platform and Operating System used
2. Dummy data that has caused this issue