Share this article
Improve this guide
FIX: Arduino was not declared in this scope error
2 min. read
Updated onOctober 4, 2023
updated onOctober 4, 2023
Share this article
Improve this guide
Read our disclosure page to find out how can you help Windows Report sustain the editorial teamRead more
Key notes
Arduino users often face the sameerror–was not declared in this scope– when trying a code they’ve made.
Let us help you out if you happen to be new to Arduino coding as well. When you get this annoyingerrorwhile compiling your code, there are a few quick fixes to apply.
How can I fix Arduino error was not declared in this scope?
1. Always declare a variable before assigning a value to it
Are you seeing thenumber was not declared in this scopeerror? Then, the problem most likely resides in not declaring the number variable to begin with.
A variable inArduinois a place to store a piece of data, with a name, a value, and a type. Most people tend to use the variable number in their loop function.
However, they need to define a variable before they use it elsewhere.
2. Make sure the loop is not missing its closing brace
If the sameerrorkeeps coming up even after creating a variable and giving it a value, pay more attention to the little things.
Even without a simple accolade, the compiler gets mixed signals since the loop is not closed and may give you these errors in return.
Things are no different for extra semicolons or functions that are not defined properly.
3. Comment the Serial1 if you use Arduino Uno
In case of getting theSerial1 was not declared in this scopeerror, chances are yourArduinohas no Serial1.
Assuming that you useArduinoUno, you need to comment the Serial1 and un-comment the SoftwareSerial part in order to solve the problem.
Have you tried to apply the above tricks? Let us know if they proved to be helpful in solving theArduinoerrorwas not declared in this scope.
If you know any other working solutions, feel free to share them by using the comments area below.
[wl_navigator]
Vlad Turiceanu
Windows Editor
Passionate about technology,Windows, and everything that has a power button, he spent most of his time developing new skills and learning more about the tech world.
Coming from a solid background in PC building and software development, with a complete expertise in touch-based devices, he is constantly keeping an eye out for the latest and greatest!
User forum
0 messages
Sort by:LatestOldestMost Votes
Comment*
Name*
Email*
Commenting as.Not you?
Save information for future comments
Comment
Δ
Vlad Turiceanu
Windows Editor
Coming from a solid background in PC building and software development, he’s a Windows 11 Privacy & Security expert.
