noVNC 404 Error

Describe the bug
When i try to connect to vnc.html, it says:

noVNC encountered an error:

Unexpected token '<'
SyntaxError: Unexpected token '<'
at https://[VNC-HOST-URL]/app/ui.js:1806:66

To reproduce
Steps to reproduce the behavior:

1. Go to '...'
2. Click on '....'
3. Scroll down to '....'
4. See error

Expected behavior
I expected the 404 error to be resolved.

Screenshots

Client (please complete the following information):

• OS: Ubuntu 24.04
• Browser: Microsoft Edge
• Browser version: Unknown

Server (please complete the following information):

• noVNC version: 1.6.0
• VNC server: 5090
• WebSocket proxy: 6080

Additional context

[CendioOssman]

There is no line 1806 in ui.js. It sounds like something is corrupting the file.

What web server are you using to serve noVNC?

Im currently using an software named "Northflank" To host this.

@CendioOssman If you want my dockerfile, it is

FROM debian:stable-slim

# Build arguments
ARG DEF_VNC_SCREEN=0
ARG DEF_VNC_DISPLAY=0
ARG DEF_VNC_RESOLUTION=1365x911
ARG DEF_VNC_PASSWORD=edgeadmin
ARG DEF_VNC_PORT=5900
ARG DEF_NOVNC_WEBSOCKIFY_PORT=6080
ARG DEF_STARTING_WEBSITE_URL=https://www.google.com
ARG DEF_LANG=en_US.UTF-8
ARG DEF_LC_ALL=C.UTF-8
ARG DEF_CUSTOMIZE=false
ARG DEF_CUSTOM_ENTRYPOINTS_DIR=/app/custom_entrypoints_scripts
ARG DEF_AUTO_START_BROWSER=true
ARG DEF_AUTO_START_XTERM=true
ARG DEF_DEBIAN_FRONTEND=noninteractive
ARG DEF_AUTO_START_WM=true
ARG DEF_AUTO_START_X11VNC=true
ARG DEF_AUTO_START_XVFB=true
ARG DEF_AUTO_START_NOVNC=true

# Edge browser options
ARG DEF_BROWSER_OPTIONS=--no-sandbox\ --disable-dev-shm-usage

ARG DEF_X11VNC_OPTIONS=
ARG DEF_XVFB_OPTIONS=
ARG DEF_WM_OPTIONS=
ARG DEF_NOVNC_OPTIONS=
ARG DEF_XTERM_OPTIONS=

# Environment vars
ENV DISPLAY=:${DEF_VNC_DISPLAY}.${DEF_VNC_SCREEN} \
    VNC_SCREEN=${DEF_VNC_SCREEN} \
    VNC_DISPLAY=${DEF_VNC_DISPLAY} \
    VNC_RESOLUTION=${DEF_VNC_RESOLUTION} \
    VNC_PASSWORD=${DEF_VNC_PASSWORD} \
    VNC_PORT=${DEF_VNC_PORT} \
    NOVNC_WEBSOCKIFY_PORT=${DEF_NOVNC_WEBSOCKIFY_PORT} \
    STARTING_WEBSITE_URL=${DEF_STARTING_WEBSITE_URL} \
    LANG=${DEF_LANG} \
    LC_ALL=${DEF_LC_ALL} \
    CUSTOMIZE=${DEF_CUSTOMIZE} \
    CUSTOM_ENTRYPOINTS_DIR=${DEF_CUSTOM_ENTRYPOINTS_DIR} \
    AUTO_START_BROWSER=${DEF_AUTO_START_BROWSER} \
    AUTO_START_XTERM=${DEF_AUTO_START_XTERM} \
    DEBIAN_FRONTEND=${DEF_DEBIAN_FRONTEND} \
    AUTO_START_WM=${DEF_AUTO_START_WM} \
    AUTO_START_X11VNC=${DEF_AUTO_START_X11VNC} \
    AUTO_START_XVFB=${DEF_AUTO_START_XVFB} \
    AUTO_START_NOVNC=${DEF_AUTO_START_NOVNC} \
    BROWSER_OPTIONS="${DEF_BROWSER_OPTIONS}" \
    X11VNC_OPTIONS=${DEF_X11VNC_OPTIONS} \
    XVFB_OPTIONS=${DEF_XVFB_OPTIONS} \
    WM_OPTIONS=${DEF_WM_OPTIONS} \
    NOVNC_OPTIONS=${DEF_NOVNC_OPTIONS} \
    XTERM_OPTIONS=${DEF_XTERM_OPTIONS}

# Install Edge + Desktop stack
RUN set -e; \
    apt update && \
    apt install -qqy wget gnupg && \
    wget -q https://packages.microsoft.com/keys/microsoft.asc -O- \
        | gpg --dearmor -o /usr/share/keyrings/microsoft.gpg && \
    echo "deb [arch=amd64 signed-by=/usr/share/keyrings/microsoft.gpg] https://packages.microsoft.com/repos/edge stable main" \
        > /etc/apt/sources.list.d/microsoft-edge.list && \
    apt update && \
    apt install -qqy \
        tini \
        supervisor \
        bash \
        xvfb \
        x11vnc \
        novnc \
        websockify \
        fluxbox \
        xterm \
        nano \
        microsoft-edge-stable && \
    apt autoremove --purge -y && \
    apt clean && \
    rm -rf /var/lib/apt/lists/*

# Directories
RUN mkdir -p /etc/supervisor.d /app/conf.d ${DEF_CUSTOM_ENTRYPOINTS_DIR} /shell /var/log/supervisor

# Copy configs
COPY supervisord.conf /etc/supervisor.d/supervisord.conf
COPY conf.d/ /app/conf.d/
COPY conf.d/browsers/edge.conf /app/conf.d/

# New entrypoint system
COPY shell/master.sh /shell/master.sh
COPY shell/user.sh /shell/user.sh

RUN chmod +x /shell/master.sh /shell/user.sh

COPY images/favicon.png /usr/share/novnc/app/images/favicon.png
COPY images/custom.js /usr/share/novnc/app/custom.js

# Fix login page favicon and title (vnc.html)
RUN sed -i 's|<link rel="shortcut icon".*|<link rel="shortcut icon" href="images/favicon.png">|' /usr/share/novnc/vnc.html && \
    sed -i 's|<title>.*</title>|<title>testweb</title>|' /usr/share/novnc/vnc.html
# Expose required ports
EXPOSE ${VNC_PORT} ${NOVNC_WEBSOCKIFY_PORT}

# Entrypoint
ENTRYPOINT ["/usr/bin/tini", "--", "/shell/user.sh"]
CMD []

[CendioOssman]

Nothing obvious there. What do you get if you open https://[VNC-HOST-URL]/app/ui.js? It should look basically the same as https://raw.githubusercontent.com/novnc/noVNC/refs/heads/master/app/ui.js.