Application-specific initialization failed: couldn't connect to display ":0.0"

[jcrademacher]

I installed xcircuit following the instructions page. When I run xcircuit I get the following message:

application-specific initialization failed: couldn't connect to display ":0"
Error in startup script: couldn't connect to display ":0"
    while executing
"load /usr/lib/x86_64-linux-gnu/libtk8.6.so Tk"
    ("package ifneeded Tk 8.6.10" script)
    invoked from within
"package require Tk $tcl_version"
    invoked from within
"if {$tcl_version < 8.0} {
    return -code error "tkcon requires at least Tcl/Tk8"
} else {
    package require Tk $tcl_version
}"
    (file "/usr/local/lib/xcircuit-3.10/tkcon.tcl" line 44)

[RTimothyEdwards]

What are you running on, and how did you invoke XCircuit? The display ":0" is generally what the DISPLAY environment variable is set to, and is supposed to match the X11 display.

[jcrademacher]

I am running on Ubuntu WSL. I simply typed xcircuit into bash. What is the X11 display?

[RTimothyEdwards]

Oh, this is the Windows-10 thing. Then you just need to be running an X server application to handle the graphics calls from xcircuit. I understand there are several good free-to-download X server applications available for Windows. Read the section "Running Graphical Applications" in https://wiki.ubuntu.com/WSL