Input Dialog: Object reference not set to an instance of an object

[Nahul_Alaguraj]

I am a beginner with respect to UiPath and I am following a state machine tutorial
the link to it as follows
and in the input dialog I keep running into the error as mentioned in the title

I hope this image has enough details

thank you

[sonaliaggarwal47 (Sonali Aggarwal)]

Hi @Nahul_Alaguraj

This error means that variable or arguments being used in the activity are not initialized/doesn’t have any value.

Can you please check if the variable you are using jn the activity actually has a value?

Run the process in debug mode and watch from locals panel the value that’s coming in variable.

Or put log message before the activity to print values of variables being used jn the activity. Thai will help you understand the root cause.

[yedukondaluaregala (YK)]

@Nahul_Alaguraj

Welcome to community..!

This issue may occurred due to scope of the of the variable. Do the below checks,

remove the amountvariable from input folder and type first three letter in the same filed of this variable (amount) and see whether you are getting the full name of the variable in suggestions section if not that means you created that variable out of scope.

Make sure whatever you created variable it should be inside scope.

delete the variable from variable panel, and go to the input dialogue activity, remove the existing value entered field and there press ctrl+k and give the name of your variable.
and change the scope of the variable based on your logic.
look below video once
https://youtu.be/Yb-Ox9xGFh0?si=Hw_uhIHG8qiafw93

[SorenB (Søren Schytz Birk)]

Hi @Nahul_Alaguraj

The error indicates that you have a variable that is not initialized.
You can use the Locals panel to troubleshoot the activity.

Also perhaps take a look at this Tutorial:

Variables and data types in practice

About this tutorial This tutorial aims to give a beginner friendly approach to topics such as data types, variables, arguments, type mismatch and scoping. It is not intended as a deep dive but more as a reference to look up when/if problems arise. What is a variable (in UiPath terms)? Variable = a “box” that holds data Every box has: Name Data Type Scope Value Variables (and Arguments) can be viewed and configured via the Data Manager. [1-variable] The 4 most common data types Data type…

Regards
Soren

[happychenxy]

I met the same problem,I changed “UiPath.system.activities” from 2026version into 2025version. and it solved. so maybe just the version compatibility problems.

[Hara_Gopal]

this not a scope issue. the variable is null or empty until the user enters a value. this version of UiPath is kaput. somebody would have vibe coded it

[chinthakayala_karthik (Karthik)]

Hello @Nahul_Alaguraj,

Looks like this is an issue with specific version of activity.

I tried with V25.12.2, V26.2.0, V26.2.1, V26.2.2 and then V25.12.2 is working where as V26.* versions are failing.

Try downgrade system activities to V25.12.2 and try.

Thanks,
karthik

[chinthakayala_karthik (Karthik)]

Hello @Nahul_Alaguraj,

There is an issue with the System activities version. Please upgrade UiPath.System.Activities to v26.2.3

Thanks,
Karthik

[angel_lirh (Luis)]

I did this and it is working now, thanks

[massimo.cappelli]

I did the same and indeed now it is working.