The questioner must provide all information to reproduce the error, in particular, the minimal working code that can be simply copy-and-pasted and executed.
The following code probably reproduces the error. See Mesh grid in Julia - #3 by genkuroki
using Plots
f(t, x) = exp(-x^2/(2t))/√(2π*t)
u(t, x) = f(t+0.1, x+2) + 2f(t+0.2, x-2)
t = range(0, 3; length=101)
x = range(-5, 5; length=101)
T = u.(t', x)
surface(t, x, T; colorbar=false,
xlabel="t", ylabel="x", zlabel="T",
camera=(30, 70), color=reverse(cgrad(:RdYlBu_11)))
The code above works fine in my Windows 10 environment.
Versions of packages:
@show VERSION
using Pkg
Pkg.status("Plots")
Pkg.status("PlotUtils"; mode=PKGMODE_MANIFEST)
Pkg.status("GR"; mode=PKGMODE_MANIFEST)
VERSION = v"1.6.2"
Status `D:\OneDrive\public\0015\Surrogates\Project.toml`
[91a5bcdd] Plots v1.20.1
Status `D:\OneDrive\public\0015\Surrogates\Manifest.toml`
[995b91a9] PlotUtils v1.0.11
Status `D:\OneDrive\public\0015\Surrogates\Manifest.toml`
[28b8d3ca] GR v0.58.1