How to Fix: Unable to open serial port error message

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A serial port may be useful, but some users have reported that the serial port message cannot be opened on their PC. This can be a big problem, and in today’s article we will show you how to solve it.

Problems with a serial port can be very annoying, especially if you tend to use the serial port frequently. When we talk about these types of problems, here are some related problems that have been reported by users:

  • Connection to com1 Windows 10, com3 could not be opened – This problem can sometimes occur if you do not have the required drivers. To solve the problem, you must update the serial port driver and verify that it solves your problem.
  • Putty cannot open Windows 10 serial port – Sometimes this problem can occur due to some Windows services. This is not a big problem, and you can solve it by disabling these services.
  • Access to the serial interface com1 cannot be opened – This problem may occur due to problems with the serial interface. To solve the problem, temporarily disable the serial port and see if it helps.
  • Com port cannot be opened win error code 5, 123, 32 – These are some common problems that can occur with a serial port, but you should be able to solve most of them with one of our solutions.

Windows may try to assign it to a COM port already in use. It seems that Windows sometimes gets an inconsistency in the registry of what has already been assigned.

To see if this is the problem (and if possible solve it), try changing the assigned COM port.

  1. Go to Device Manager > Ports (COM & LPT) > mbed Serial Port, then right-click and select Properties.
  2. Select the Port Settings tab and click Advanced.
  3. Under “COM port number”, try to select a different COM port.

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Note that Windows marks some of them as (in use), but does not consider them exhaustive, for the same reason that this problem may exist!

Try switching it to a few different unused COM ports and see if it has an effect. If not, we will dive deeper to see what Windows is reporting.

And don’t forget to unplug the power cord after the change to recharge the driver and see all the results.

Try using another cable.

I noticed that using an older USB cable sometimes leads to a poor connection of the card. It would be moody if it worked sometimes and not differently. The problem was solved with a new or even different cable.


If you enter “Hyperterminal” in the Windows Start menu, right-click after the call and select “Run as administrator”. It should help you access the serial port.

Also check which COM port it uses. To do this, follow these steps:

1. press the window+R button

2. type devmgmt.msc

3. go to ports

Now check which port is assigned to the USE serial converter and use it in the spatula.

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