Cant create Transaction item with list

[Arettu63 (Att)]

I cant create queue item with list, error text: Add Queue Item: queueItemParameters must not be null Error code: 0
My collection in Add Queue Item:

and it is not null:

[nishiijain2000 (Nishi Jain)]

Hi @Arettu63

You cannot pass List directly to a queue item.Convert it to a JSON string or split it into multiple queue items.serialized list to json

JsonConvert.SerializeObject(Upload_LIST)
Then pass it like this

New Dictionary(Of String, Object) From {
{“UploadList”, uploadListJson}
}
Deserialize back for consumer using

JsonConvert.DeserializeObject(Of List(Of String))(TransactionItem.SpecificContent(“UploadList”).ToString)

Hope it help
Thanks & Happy Automation

[Maheep_Tiwari]

Hi @Arettu63 ,

You cannot pass a List directly to a UiPath queue item. Serialize the list to JSON using JsonConvert.SerializeObject, store it as a string in Specific Content, and then deserialize it back to a List in the consumer using JsonConvert.DeserializeObject.

[nishiijain2000 (Nishi Jain)]

Hi @Arettu63
If solution works for you please mark as solved so thread will be closed

Thanks

[ashokkarale]

@Arettu63

Add Queue Item: queueItemParameters must not be null Error code: 0

The error message you are getting is due to the list variable is being null. If there are values you should have been getting error

Add Queue Item: Property values must be simple (like numbers or text) and not complex or composite data types (like objects or arrays). Error code: 1000

This error clearly specifies that you can’t add complex datatypes to queue as it is. You must deserialize it and add it to queue.

[MohammedShabbir (shabbir.qs)]

@Arettu63

I cant create queue item with list, error text: Add Queue Item: queueItemParameters must not be null Error code: 0
My collection in Add Queue Item:

Hi @Arettu63

You can serialize the List
Newtonsoft.Json.JsonConvert.SerializeObject(listStr)

Main.xaml (10.7 KB)

[Anil_G (Anil Gorthi)]

@Arettu63

First thing complex data types are not supported for adding into queue ..so you cannot add list

now coming to error looks like there might be two variables with same name or the vsalue being null somehow…better check the values again properly on failure..but as said list cannot be added directly

cheers

[MohammedShabbir (shabbir.qs)]

If you need any further help related to this feel free to ask and if this solution works, please mark it as the Accepted Solution

[Monali_Vekariya (Mona)]

Hi @Arettu63

The issue is that UiPath Orchestrator cannot store a List<T> directly as a Queue Item argument. It only supports simple types like Strings, Integers, or Booleans.

The Fix: You need to convert the list into a single string before adding it to the queue.

1. In “Add Queue Item”: Change the value of testList to: String.Join(",", Upload_LIST)
2. To retrieve it later: In your worker process, turn it back into a list using: yourListVariable = rowValue.Split(","c).ToList()

Just flatten the list into a string using String.Join(",", Upload_LIST) in your Add Queue Item activity. Then, when you get the transaction item later, use .Split to turn it back into a list. This will get rid of the null parameter error immediately."