Pi 4B Won't boot without HDMI cable plugged to Monitor

[yitasha]

Hi Guys, I am a beginner with Pi.
I got a Pi4 with 4GB ram and Rasbian Full Desktop installed, SenseHAT attached as well.
I did the wpa_wifi config file and it works fine with Monitor attached.

When I try to boot Pi4 without monitor plugged in, it won't boot.
If I boot first and then plug HDMI 1 second later, it still won't boot.

If I boot with monitor plugged in, it works fine even I unplug it later.

So my conclusion is that it won't boot without HDMI cable connected to a monitor.

Because I am trying to do headless ssh connection when I am outside.
Anyone can help?

[FTrevorGowen]

Hi Guys, I am a beginner with Pi.
I got a Pi4 with 4GB ram and Rasbian Full Desktop installed, SenseHAT attached as well.
I did the wpa_wifi config file and it works fine with Monitor attached.

When I try to boot Pi4 without monitor plugged in, it won't boot.
If I boot first and then plug HDMI 1 second later, it still won't boot.

If I boot with monitor plugged in, it works fine even I unplug it later.

So my conclusion is that it won't boot without HDMI cable connected to a monitor.

Because I am trying to do headless ssh connection when I am outside.
Anyone can help?

How do you know it's not booting (eg. what do the red PoWeR and green ACTivity leds do?)
Are you (attempting to) boot to desktop or command line. With or without auto-login.
How did you enable networking, SSH (and, maybe, also VNC) etc? Eg. via raspi-config (GUI or command-line), and you have changed the default password haven't you!
What are using to SSH in from and how? (eg PuTTY**)
If you're trying to VNC into a (temporarily) headless system either set up a "fallback" screen resolution or login via PuTTY (or similar) and make use of RealVNC's virtual mode to set the geometry****.
Trev.
** FWIW a somewhat old set of examples are here: https://www.cpmspectrepi.uk/raspberry_p ... aspPi.html
**** https://www.cpmspectrepi.uk/raspberry_p ... uster.html

[thagrol]

I run mine headless but I've noticed this come up a few times on the forum.

From what I recall it's due to a change in the hardware and driver setup for the 4B. If no monitor is detected, no frame buffer is created, so X (the desktop) won't start.

The fix seemed to be to force a resolution/HDMI mode in /boot/config.txt.

Don't ask me how, I've never had to do that as all my Pi are headless. A forum search will probably tell you.

[yitasha]

Hi @ FTrevorGowen
I know it's not booting because my SenseHAT display is ON, when it boots successfully, SenseHAT will be OFF.
The red power light is fine, if I boot without video HDMI output, the SenseHAT stays solid lighting.
I am trying to boot it up with WIFI connection, so I can SSH into it from another PC.
I enabled networking with WPA_config file filled in with my home network, if I boot with MONITOR connected, the WIFI will connect automatically.
SO with monitor, everything works perfectly fine, WIFI, booting success, ssh via cmd line are all good.
My VNC works if I boot with Monitor and VNC from my another PC or laptop, I can get Pi's desktop successfully.

Hi @thagrol
I agree, something is wrong with my Pi 4, it's like won't boot successfully without Monitor ALREADY plugged in.
If a HDMI output -> Monitor/TV is not plugged in upon booting, the Pi can be started with RED power light on, but it won't boot successful because it doesn't have a video output???

I have few friends with Pi 3B+ or 4B, they have same issue...
I guess I'll try reinstall it and try to force a resolution/HDMI output mode even without HDMI plugged in.

[klricks]

……..I guess I'll try reinstall it and try to force a resolution/HDMI output mode even without HDMI plugged in.

No need to reinstall anything. As mentioned you need to force a resolution setting. The easiest way to do that is to use sudo raspi-config to set a resolution of your choice. Choose anything other than default monitor resolution.

[yitasha]

……..I guess I'll try reinstall it and try to force a resolution/HDMI output mode even without HDMI plugged in.

No need to reinstall anything. As mentioned you need to force a resolution setting. The easiest way to do that is to use sudo raspi-config to set a resolution of your choice. Choose anything other than default monitor resolution.

Yea, I tried to enable the hdmi hotplug at config.txt , now it works, is able to boot successfully without HDMI or with HDMI.

[GnetworkGnome]

Ran into the same problem with the same configuration, SenseHat and all. Had to resolve it in the same way in /boot/config.txt:

# uncomment if hdmi display is not detected and composite is being output
hdmi_force_hotplug=1