Im getting this error: "Error getting transaction data for Transaction Number: 1. Value cannot be null. Parameter name: source at Source: If" in Assignment nr. 1 from Advanced Level and i don't know where is the mistake




Hi @Ionut_Istrate

please initialize the TransactionNumber with 1 and try once again.

based on that you are page numbers processed, if you leave it null it throws an error.



The same… this my main menu and in the right corner you have the errors…


are you in Assignment 1 or 2…?

if its assignment 2 then remove that activity which throwing error, its not needed.



it’s 1.


i guess you have not passed arguments to GetTransactiondata(), can you verify once…

in_transactionNumber = TransactionNumber


This is my Get transaction data… i don t know where i need to change the values

GetTransactionData.xaml (10.9 KB)


GetTransactionData.xaml (10.1 KB)

i have sent mine, check and update where ever needed.



it’s the same yours with mine. Anyway Thank you very much.


in that case put a breakpoint to Gettransactiondata workflow and use debug mode to see whats the prob…



Please verify that you have value in in_WIList in GetTransactionData.xaml if there no value see that you have extracted and sent the WILIst items correctly. In InitState like this


Thank you very much i already fixed. That was the mistake. Thank you all for your help.


Hi ,
I am facing same transaction number issue can any one please help on this.
I am successfully logged into ACME application, clicked on ‘work Items’ , collected all the data stored in a data table ,filtered with ‘WI5’ and ‘open’ status and filtered items stored in WIList .
Below are the argument for ‘Get Transaction Data’ WorkFlow
When I am entering into ‘Get Transaction Data’ work flow my condition is failing due to below error.
“Error getting transaction data for Transaction Number: 1. Value cannot be null. Parameter name: source at Source: UiPath.Executor”
exactly at below condition script is failing


You have not completed the argument binding.

  1. Collect Data and create out argument WIList [correct]
  2. Invoke System1 Extract Work Items - map argument WIList to a locally created variable WIList in Main(same type)
  3. Now map the WIList variable here
    Without this in below if in_WIList is null, hence the warning


Thank you for help.

It got resolved.



I am facing the same issue after following the steps too. Could you please help.Attaching screenshot for your reference.

Thanks !!!


Attaching more images for reference:



@prankurjoshi @nadim.warsi Could you please help


can you print the wilist1.count asnnd see what is the result?