# ESP32-S3's Serial monitor not working in IDE

**URL:** <https://forum.arduino.cc/t/esp32-s3s-serial-monitor-not-working-in-ide/1356285>\
**Category:** IDE 2.x\
**Created:** [February 20, 2025, 10:53pm UTC](https://forum.arduino.cc/t/esp32-s3s-serial-monitor-not-working-in-ide/1356285 "2025-02-20T22:53:25Z")\
**Posts on this page:** 20\
**Page:** 1

<div class="post-metadata">

**Author:** ![der\_leviathan\_2025](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/der_leviathan_2025/32/1108647_2.png) [@der\_leviathan\_2025](https://forum.arduino.cc/u/der_leviathan_2025)\
**Post date:** [February 20, 2025, 10:53pm UTC](https://forum.arduino.cc/t/esp32-s3s-serial-monitor-not-working-in-ide/1356285/1 "2025-02-20T22:53:25Z")

</div>

Hi there,

I am new to ESP32 and got into an issue which drives me crazy for the last 3 days or so.

The following code is successfully uploaded to ESP32-S3 but the Serial monitor receives no feedback.

```arduino
void setup() {
  Serial.begin(115200);
}

void loop() {
  Serial.println("Testing");
  delay(1000);
}

```

Arduino IDE 2.3.4  
Win 11 Pro, version 23H2  
using **ESP32S3 Dev Module** profile on a COM port via the USB connector on the board  
Board (marked USB, not COM on the back of the board, using COM fails the upload): [YD-ESP332-23 v1.3](https://www.amazon.co.uk/dp/B0DFGFV3H5)

Compiling and uploading is successful

```arduino
[...]
Writing at 0x00054af5... (100 %)
Wrote 299056 bytes (159267 compressed) at 0x00010000 in 2.9 seconds (effective 838.9 kbit/s)...
Hash of data verified.

Leaving...
Hard resetting with RTC WDT...

```

Serial Monitor running on 115200 baud is blank

Why does it not print "Testing" continuously?

I would appreciate any help with this.  
Do let me know if you need any further information.

Thank you 🙂

---

<div class="post-metadata">

**Author:** ![ptillisch](https://avatars.discourse-cdn.com/v4/letter/p/ad7895/32.png) [@ptillisch](https://forum.arduino.cc/u/ptillisch)\
**Post date:** [February 20, 2025, 11:15pm UTC](https://forum.arduino.cc/t/esp32-s3s-serial-monitor-not-working-in-ide/1356285/2 "2025-02-20T23:15:54Z")

</div>

Hi @der_leviathan_2025. A fairly unique thing about the boards that use the microcontrollers of the [**ESP32**](https://wikipedia.org/wiki/ESP32) family with native USB capability (as is the case with your board) is that they are typically configured to disable the use of their USB CDC serial port in the sketch by default.

That default disabled configuration is appropriate when your sketch doesn't use the serial port, but in cases where you do need it (such as when your sketch calls `Serial.println`, etc.), then it is necessary to configure the board so that the port will be enabled. Fortunately this is quite easy since the ESP32 boards platform developers configured the board definition to produce a custom board options menu you can use to enable or disable the port as needed via the Arduino IDE user interface.

Please try this:

1. Select **Tools \> USB CDC On Boot \> Enabled** from the Arduino IDE menus.
2. Upload the sketch to your board again, just as you did before.

Now check the Serial Monitor. Hopefully you will now see the expected output from the board there.

---

<div class="post-metadata">

**Author:** ![der\_leviathan\_2025](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/der_leviathan_2025/32/1108647_2.png) [@der\_leviathan\_2025](https://forum.arduino.cc/u/der_leviathan_2025)\
**Post date:** [February 20, 2025, 11:36pm UTC](https://forum.arduino.cc/t/esp32-s3s-serial-monitor-not-working-in-ide/1356285/3 "2025-02-20T23:36:10Z")

</div>

Hi @ptillisch,

Thank you so much for coming back to me so quickly 🙂

I've changed the **USB CDC On Boot** to **Enabled** but unfortunately, after a re-upload, the Serial Monitor still does not show any messages.

 ![image](https://europe1.discourse-cdn.com/arduino/original/4X/4/5/e/45e8386408dfcfcaf5c540509971477bdc0d1bbc.png)

 ![image](https://europe1.discourse-cdn.com/arduino/original/4X/0/a/c/0ac45a8cb1342cf9b08b0b0176055c4629465cc5.png)

On my quest to get this up and running, I've tried multiple things, so I hope I have not changed any important settings 🙈

I hope the screen capture above might spark further ideas.

Thank you 🙂

---

<div class="post-metadata">

**Author:** ![sonofcy](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/sonofcy/32/1283617_2.png) [@sonofcy](https://forum.arduino.cc/u/sonofcy)\
**Post date:** [February 21, 2025, 12:16am UTC](https://forum.arduino.cc/t/esp32-s3s-serial-monitor-not-working-in-ide/1356285/4 "2025-02-21T00:16:49Z")

</div>

Have you pressed the reset button?

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<div class="post-metadata">

**Author:** ![der\_leviathan\_2025](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/der_leviathan_2025/32/1108647_2.png) [@der\_leviathan\_2025](https://forum.arduino.cc/u/der_leviathan_2025)\
**Post date:** [February 21, 2025, 12:28am UTC](https://forum.arduino.cc/t/esp32-s3s-serial-monitor-not-working-in-ide/1356285/5 "2025-02-21T00:28:34Z")

</div>

I am pretty sure, I've tried the following combinations:

1. Holding the BOOT button on upload and releasing once it was finished
2. Pushing RST butto after upload
3. Both of the above combined
4. Before upload holding BOOT, pushing RST, releasing BOOT
5. Combination of point 4, then point 2

I am not in front of my PC anymore, but will try them tomorrow again with CDC enabled. Maybe it makes a difference 🤔

Nevertheless, thank y'all for your input and help, much appreciated.

---

<div class="post-metadata">

**Author:** ![sonofcy](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/sonofcy/32/1283617_2.png) [@sonofcy](https://forum.arduino.cc/u/sonofcy)\
**Post date:** [February 21, 2025, 12:43am UTC](https://forum.arduino.cc/t/esp32-s3s-serial-monitor-not-working-in-ide/1356285/6 "2025-02-21T00:43:14Z")

</div>

The last time I had a situation like that, it was the cable. I tested it on a USB continuity checker, and it was ok, but I decided to change it in any case, and the problem was solved. I then cut the other cable in half and tossed it.

---

<div class="post-metadata">

**Author:** ![der\_leviathan\_2025](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/der_leviathan_2025/32/1108647_2.png) [@der\_leviathan\_2025](https://forum.arduino.cc/u/der_leviathan_2025)\
**Post date:** [February 21, 2025, 4:41pm UTC](https://forum.arduino.cc/t/esp32-s3s-serial-monitor-not-working-in-ide/1356285/7 "2025-02-21T16:41:09Z")

</div>

So, I've tried all from post #5 with no success ☹

I also tried a new cable and USB port on my PC, still no success.

As I do not have a good setup to test continuity of each contact of a USB cable, I've just connected my phone with the PC using the cables and was able to charge, up and download with any problems, which tells me the cables are working fine, right?

This really bugs me as I have tried everything 😭  
Happy to switch to a different board as well, if that makes it easier...  
(by the way, this is my second ESP32 board of the same make with the same issue!)

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<div class="post-metadata">

**Author:** ![sonofcy](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/sonofcy/32/1283617_2.png) [@sonofcy](https://forum.arduino.cc/u/sonofcy)\
**Post date:** [February 21, 2025, 6:01pm UTC](https://forum.arduino.cc/t/esp32-s3s-serial-monitor-not-working-in-ide/1356285/8 "2025-02-21T18:01:59Z")

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I just pulled out one of my esp32-s3 boards and uploaded the blink sketch. I am NOT including a video of the blink running as vids are not allowed but if you want proof, I can figure something out to get it to you, screen shots of Tools and Board Data plus photos front and back of my board.

 ![IMG_9372](https://europe1.discourse-cdn.com/arduino/original/4X/1/f/3/1f3149b9e1b2b8054f113b3707352f228df5a3cc.jpeg)  
 ![IMG_9373](https://europe1.discourse-cdn.com/arduino/original/4X/c/b/3/cb36377d5a5770f66833589f0faaec8314aaabb9.jpeg)  
 ![Screenshot 2025-02-21 at 12.57.48](https://europe1.discourse-cdn.com/arduino/original/4X/3/4/5/3459faffa726efbdf390b4eeb9f00f0bb89ef15d.png)  
 ![Screenshot 2025-02-21 at 12.58.03](https://europe1.discourse-cdn.com/arduino/original/4X/e/9/7/e97c85e6df43eafac2a7dc462f0134aa1af6d312.png)

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<div class="post-metadata">

**Author:** ![der\_leviathan\_2025](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/der_leviathan_2025/32/1108647_2.png) [@der\_leviathan\_2025](https://forum.arduino.cc/u/der_leviathan_2025)\
**Post date:** [February 21, 2025, 6:20pm UTC](https://forum.arduino.cc/t/esp32-s3s-serial-monitor-not-working-in-ide/1356285/9 "2025-02-21T18:20:51Z")

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Ill have a look into this in a little while. Which blink sketch did you use? Can you post the code here, please? 🙇‍♂️

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<div class="post-metadata">

**Author:** ![sonofcy](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/sonofcy/32/1283617_2.png) [@sonofcy](https://forum.arduino.cc/u/sonofcy)\
**Post date:** [February 21, 2025, 6:28pm UTC](https://forum.arduino.cc/t/esp32-s3s-serial-monitor-not-working-in-ide/1356285/10 "2025-02-21T18:28:20Z")

</div>

It's the IDE basic sample.

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<div class="post-metadata">

**Author:** ![sonofcy](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/sonofcy/32/1283617_2.png) [@sonofcy](https://forum.arduino.cc/u/sonofcy)\
**Post date:** [February 21, 2025, 6:55pm UTC](https://forum.arduino.cc/t/esp32-s3s-serial-monitor-not-working-in-ide/1356285/11 "2025-02-21T18:55:56Z")

</div>

I then tried your original sketch and NO serial output. I then tried my default sketch, which also did nothing. I then added a print followed by a 1-second delay and could see the red led blinking at 1 sec interval. I then changed to a 5-second delay, and the red LED now blinks at 5 5-second intervals.  
Something is preventing the serial output from showing up. I have to go out but maybe someone will remember what the secret is.

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<div class="post-metadata">

**Author:** ![der\_leviathan\_2025](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/der_leviathan_2025/32/1108647_2.png) [@der\_leviathan\_2025](https://forum.arduino.cc/u/der_leviathan_2025)\
**Post date:** [February 21, 2025, 6:59pm UTC](https://forum.arduino.cc/t/esp32-s3s-serial-monitor-not-working-in-ide/1356285/12 "2025-02-21T18:59:48Z")

</div>

Thank you @sonofcy

I've tried the Blink default sketch from Arduino (File -\> Examples -\> 01.Basics -\> Blink) but unfortunately, after the upload the onboard LED does not blink as expected ☹

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<div class="post-metadata">

**Author:** ![sonofcy](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/sonofcy/32/1283617_2.png) [@sonofcy](https://forum.arduino.cc/u/sonofcy)\
**Post date:** [February 21, 2025, 8:33pm UTC](https://forum.arduino.cc/t/esp32-s3s-serial-monitor-not-working-in-ide/1356285/13 "2025-02-21T20:33:34Z")

</div>

Ok, take the same pictures and screen grabs as I did so we can see what the heck the difference is.

---

<div class="post-metadata">

**Author:** ![der\_leviathan\_2025](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/der_leviathan_2025/32/1108647_2.png) [@der\_leviathan\_2025](https://forum.arduino.cc/u/der_leviathan_2025)\
**Post date:** [February 21, 2025, 8:49pm UTC](https://forum.arduino.cc/t/esp32-s3s-serial-monitor-not-working-in-ide/1356285/14 "2025-02-21T20:49:55Z")

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Here we go

 ![image](https://europe1.discourse-cdn.com/arduino/original/4X/d/f/5/df5a1f8610ae5c3985462b34964885a7a1936d7a.jpeg)  
 ![image](https://europe1.discourse-cdn.com/arduino/original/4X/4/1/4/41484a424f0461e48c7cbd1a06df42b4af42cd7a.jpeg)

 ![image](https://europe1.discourse-cdn.com/arduino/original/4X/8/5/0/85007c73d383ff5a7a851e3ec6e155c3feb8cdcd.png)  
I've tried both enabling and disabling **USB CDC On Boot**

 ![image](https://europe1.discourse-cdn.com/arduino/original/4X/c/7/e/c7ed7cb90d5b54affef46ddd6a5d6451ab938e09.png)  
Funny enough I do not get a serial number back

---

<div class="post-metadata">

**Author:** ![sonofcy](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/sonofcy/32/1283617_2.png) [@sonofcy](https://forum.arduino.cc/u/sonofcy)\
**Post date:** [February 21, 2025, 9:04pm UTC](https://forum.arduino.cc/t/esp32-s3s-serial-monitor-not-working-in-ide/1356285/15 "2025-02-21T21:04:31Z")

</div>

I am going to make a wild guess and say the no serial number means a clone or fake board.

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<div class="post-metadata">

**Author:** ![der\_leviathan\_2025](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/der_leviathan_2025/32/1108647_2.png) [@der\_leviathan\_2025](https://forum.arduino.cc/u/der_leviathan_2025)\
**Post date:** [February 21, 2025, 9:08pm UTC](https://forum.arduino.cc/t/esp32-s3s-serial-monitor-not-working-in-ide/1356285/16 "2025-02-21T21:08:04Z")

</div>

After purchasing the board, i found out exactly that, it is a cloned board spattered all over Amazon 😒

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<div class="post-metadata">

**Author:** ![der\_leviathan\_2025](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/der_leviathan_2025/32/1108647_2.png) [@der\_leviathan\_2025](https://forum.arduino.cc/u/der_leviathan_2025)\
**Post date:** [February 21, 2025, 9:09pm UTC](https://forum.arduino.cc/t/esp32-s3s-serial-monitor-not-working-in-ide/1356285/17 "2025-02-21T21:09:02Z")

</div>

Let me see if i can get a genuine board online and maybe that will give me the desired result

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<div class="post-metadata">

**Author:** ![der\_leviathan\_2025](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/der_leviathan_2025/32/1108647_2.png) [@der\_leviathan\_2025](https://forum.arduino.cc/u/der_leviathan_2025)\
**Post date:** [February 21, 2025, 9:11pm UTC](https://forum.arduino.cc/t/esp32-s3s-serial-monitor-not-working-in-ide/1356285/18 "2025-02-21T21:11:44Z")

</div>

Anything I should have an eye out for, in terms of designation/specs?

The project I am working on at the moment will need a minimum of 8 IO (4 of which I would like to use Touch input).  
I understand that this board is overkill, but I would also like to try out some stuff, before buying one board which will fit the end result of this project.

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<div class="post-metadata">

**Author:** ![sonofcy](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/sonofcy/32/1283617_2.png) [@sonofcy](https://forum.arduino.cc/u/sonofcy)\
**Post date:** [February 21, 2025, 9:22pm UTC](https://forum.arduino.cc/t/esp32-s3s-serial-monitor-not-working-in-ide/1356285/19 "2025-02-21T21:22:00Z")

</div>

Did you see my post #11? I can get it to blink, but no Serial out. There is a red LED that blinks at the same frequency as the Serial. println statement, but no output.  
I wonder if this is a Boards 3 issue, have you tried backleveling your espressif esp32 boards to 2.0.17? I will also try.

---

<div class="post-metadata">

**Author:** ![sonofcy](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/sonofcy/32/1283617_2.png) [@sonofcy](https://forum.arduino.cc/u/sonofcy)\
**Post date:** [February 21, 2025, 9:27pm UTC](https://forum.arduino.cc/t/esp32-s3s-serial-monitor-not-working-in-ide/1356285/20 "2025-02-21T21:27:27Z")

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Nope, not a Boards 3 issue.

[Next page](https://forum.arduino.cc/t/esp32-s3s-serial-monitor-not-working-in-ide/1356285.md?page=2)