I'm having the same problem Steve Thomas has:

Windows 10 PC

Radio Kenwood TM-281

Cable - Prolific USB-to-Serial Comm Port (COM3)

Driver 3.2.0.0 7/31/2007

Run CHIRP daily-20190222

Select Download from Radio

Confirm Radio & Port

No response from CHIRP after 5 minutes

Re-select Download from Radio

Error popup reads An error has occurred

could not open port COM3: [Error 5] Access is denied

Quit CHIRP

Open MCP-1A

Select Read>All

Reading the data from the transceiver, and data is displayed in window

Select File>Open - choose "test" mcp file. Full programming data is displayed

Select Write>all

Popup asks "Do you want to write the data to the transceiver?" Select Yes

Writing the data to the transceiver, and radio is programmed with contents of "test" mcp file

So the problem does not seem to be with the cable or the radio, since MCP-1A can talk to the radio.

So it appears that Steve and I have exactly the same problem with CHIRP. Except Steve's is first time programming and mine is after a reset or after the radio has been programmed with MCP-1A

Can any TM-281 users offer other suggestions, or CHIRP experts/developers?

/Tom

K6IGY

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Date: Sun, 24 Feb 2019 20:00:17 -0600
From: Steve Thomas < stevet@alertcpr.com>
Subject: [chirp_users] Error Programming Kenwood TM281
To: chirp_users@intrepid.danplanet.com
Message-ID: < 37314aab-cfa8-8fc0-1cd8-6663c04870e3@alertcpr.com>
Content-Type: text/plain; charset="windows-1252"

I am trying to program my Kenwood TM281 for the first time. I'm using
Windows 10.? I previously ran Chirp to program a Wouxon hand held and it
worked fine with that cable.

I have a Prolific cable I got from BlueMax49ers.?? The instructions said
it was a genuine Prolific chip and to use the latest drivers.? So I
checked and it is using the latest drivers (3.8.28.0).? When I started
Chirp, I plugged in the radio, and selected "Download from Radio".?? It
gave me a dialog with Com3 preselected, and I selected Kenwood and
TM281. When I clicked OK in the dialog, I get this message:

_*An ERROR Has Occurred*__*
*__*could not open port COM4: [Error 5] Access is denied.*_

I tried Com3, and got the same error.

_*An ERROR Has Occurred*__*
*__*could not open port COM3: [Error2] The System Cannot find The File
specified.*_

(this may be the original error, I don't know. I changed the com port to
Com4 before writing down what the original error was when it originally
went to Com3)
**_**_

I looked into Device Manager, and under Ports (Com and LPT) It says the
Prolific USB to Serial Comm Port (Com4)

I looked at the Properties and it says this:

Does this sound familiar?

Steve