what did i do wrong
Changing monitoring state from "Offline" to "Detecting serial connection"
Performing autodetection with 10 port/baudrate candidates: COM4@115200, COM4@250000, COM5@115200, COM5@250000, COM3@115200, COM3@250000, COM7@115200, COM7@250000, COM6@115200, COM6@250000
Trying port COM4, baudrate 115200
Connecting to port COM4, baudrate 115200
Handshake attempt #1 with timeout 2.0s
Connected to: Serial<id=0x19d134de110, open=True>(port='COM4', baudrate=115200, bytesize=8, parity='N', stopbits=1, timeout=2.0, xonxoff=False, rtscts=False, dsrdtr=False), starting monitor
Send: N0 M110 N0125
Handshake attempt #2 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #3 with timeout 2.0s
Send: N0 M110 N0125
Trying port COM4, baudrate 250000
Handshake attempt #1 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #2 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #3 with timeout 2.0s
Send: N0 M110 N0125
Trying port COM5, baudrate 115200
Connecting to port COM5, baudrate 115200
Handshake attempt #1 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #2 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #3 with timeout 2.0s
Send: N0 M110 N0125
Trying port COM5, baudrate 250000
Handshake attempt #1 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #2 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #3 with timeout 2.0s
Send: N0 M110 N0125
Trying port COM3, baudrate 115200
Connecting to port COM3, baudrate 115200
Could not open port COM3, baudrate 115200, skipping
Trying port COM3, baudrate 250000
Connecting to port COM3, baudrate 250000
Could not open port COM3, baudrate 250000, skipping
Trying port COM7, baudrate 115200
Connecting to port COM7, baudrate 115200
Could not open port COM7, baudrate 115200, skipping
Trying port COM7, baudrate 250000
Connecting to port COM7, baudrate 250000
Could not open port COM7, baudrate 250000, skipping
Trying port COM6, baudrate 115200
Connecting to port COM6, baudrate 115200
Could not open port COM6, baudrate 115200, skipping
Trying port COM6, baudrate 250000
Connecting to port COM6, baudrate 250000
Could not open port COM6, baudrate 250000, skipping
Changing monitoring state from "Detecting serial connection" to "Error"
Changing monitoring state from "Error" to "Offline after error"
Connection closed, closing down monitor
Changing monitoring state from "Offline" to "Detecting serial connection"
Performing autodetection with 7 port/baudrate candidates: COM3@115200, COM3@250000, COM3@230400, COM3@57600, COM3@38400, COM3@19200, COM3@9600
Trying port COM3, baudrate 115200
Connecting to port COM3, baudrate 115200
Could not open port COM3, baudrate 115200, skipping
Trying port COM3, baudrate 250000
Connecting to port COM3, baudrate 250000
Could not open port COM3, baudrate 250000, skipping
Trying port COM3, baudrate 230400
Connecting to port COM3, baudrate 230400
Could not open port COM3, baudrate 230400, skipping
Trying port COM3, baudrate 57600
Connecting to port COM3, baudrate 57600
Could not open port COM3, baudrate 57600, skipping
Trying port COM3, baudrate 38400
Connecting to port COM3, baudrate 38400
Could not open port COM3, baudrate 38400, skipping
Trying port COM3, baudrate 19200
Connecting to port COM3, baudrate 19200
Could not open port COM3, baudrate 19200, skipping
Trying port COM3, baudrate 9600
Connecting to port COM3, baudrate 9600
Could not open port COM3, baudrate 9600, skipping
Changing monitoring state from "Detecting serial connection" to "Error"
Changing monitoring state from "Error" to "Offline after error"
So based on the ports being attempted to connect to it seems you're using a windows machine to connect to your printer. You have to make sure you have the correct driver installed in windows for your printer. There are I think two common options typically now a days, but depends on the printer. One of the most common is the ch340 drivers. How to Install CH340 Drivers - SparkFun Learn the other common one is Creality Printer Drivers – FT232R Chip – Most Models - TH3D Studio Help Center
let's backup a step. if you power off the printer and unplug it from the machine, open device manager and look at available com ports in the ports section. Plug in printer and power it on and look for newly added COM port. If it doesn't add then the printer isn't detected. If it doesn't show up at all, or doesn't make a ding new device and show up under other devices (with question mark icon overlay) then make sure you are using a data cable and not a power only/charge cable. This can mess people up and I've seen people try up to 10 cables and finally get one that supported data. Once you have the printer being recognized and showing as a new COM port, select that COM port in OctoPrint's connection panel instead of using Auto and click connect.