Custom Activity - Value cannot be null/Unable to find package

Hi all,

I have created a simple custom activity which displays the progress bar.
It uses window-forms with ProgressBar element and it was working well. I did not change the package but recently an error started to come out. (might be connected to studio update)

Whenever I create a variable from the custom activity, (the type becomes progressBar), and I am able to use it and to continue the development normally. However if I close and open the xaml file the activity is used in, the error “Value cannot be null” pops up. It happens all the time and sometimes even without closing the workflow.

If I create the variable and assign the type myself, everything works fine without an error.

So I started digging into the activity and changed it a little bit. But when I tried to create the package, the error saying: "unable to find package System.Activities.Metadata and System.Acitivities.Core.Presentation. " came out.

I understand that those are probably old ‘windows workflow foundation’ packages and are maintained by UiPath. So I checked myget, added additional paths to UiPath-dev feed (although I had one already). And tried again.
This time I get this error:

Severity Code Description Project File Line Suppression State
Error NU1102 Unable to find package System.Activities.Metadata with version (>= 6.0.0)

  • Found 3 version(s) in UiPath [ Nearest version: 1.0.0-alpha003 ]
  • Found 3 version(s) in Uipathv2 [ Nearest version: 1.0.0-alpha003 ]
  • Found 3 version(s) in MyGet [ Nearest version: 1.0.0-alpha003 ]
  • Found 0 version(s) in Microsoft Visual Studio Offline Packages
  • Found 0 version(s) in
  • Found 0 version(s) in NuGet GT.StatusProgressBar.Activities (path)\GT.StatusProgressBar.Activities.csproj 1

which lowkey makes sense since I got this warning as well.

Severity Code Description Project File Line Suppression State
Warning NU1603 GT.StatusProgressBar.Activities depends on UiPath.Workflow (>= 6.0.0-20220909-01) but UiPath.Workflow 6.0.0-20220909-01 was not found. An approximate best match of UiPath.Workflow 6.0.0-alpha-20220106-04 was resolved. GT.StatusProgressBar.Activities.Design
(path)\GT.StatusProgressBar.Activities.Design.csproj 1

However how was I able to actually develop and publish this 2 months ago. Were the compatibile packages removed from the feed? And if so, why?

Did anyone stumbled across similar error?

Hi @GT_Ropa,

Thank you for reporting this.

Changing the topic to a feedback topic. If it is a bug your description can help the product team.

1 Like