"Sequence contains no matching element" when typing an opening brace

Whenever I type an opening brace character ( { ) in one of any activity’s fields, Studio shows this error, which is SUPER annoying. I’m running the version 2021.4.5.


Did you select the C# option while creating this project?

this is just by typing that curly bracket anywhere and on any activity? is there any specific you get this error in?

Chosen project language is VB.

The error always comes after typing the opening brace, no matter which activity/field it’s typed into.

This seems to be somehow connected to having either the Properties or Designer panel active and in ‘edit field’ mode. If I then hold down the Ctrl key and press any number key 1-9, that error pops up.

Try to see the package is updated for activities, make sure the Official source is selected in the Manage Package Source

If still issue persists may be @loginerror or @Pablito can comment

All installed packages in the project are the most recent versions already. It sure seems like the UiPath Studio itself is acting buggy.

Never experienced this with any other Studio version I’ve used. Very weird.

Can you please share a video/gif of the behaviour you are seeing?

I cannot replicate the issue with latest Studio 21.10.3.


{} isn’t a valid expression to put into the “In” so it keeps generating an error.

That’s not the underlying reason. Same error is displayed if I first fill ""} in the In field and then complete the expression with the opening brace in front, making {""} a valid IEnumerable.

Besides, UiPath Studio shouldn’t display an error popup but just show the red exclamation point in the activity block instead.

Any chance you could share a dummy project that has this issue?

Does it also happen if you create a new blank project?

Interestingly enough, I opened another project and the error did not manifest there. I then went back to the project where I had originally noticed the popup the but it didn’t appear anymore.

So, opening another project seems to have fixed the issue. Very strange.

These types of mystical bugs are the most difficult to track down, but also the most satisfying to fix :sweat_smile:

Please let us know in case it manifests itself again.

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