There are two common reasons why you might not be able to launch the OnDemand desktop session you have running:

1. You are over quota in your home directory.  Please see this article

2.  You are loading an environment in your .bashrc file that is incompatible with the OnDemand interactive desktop.  Please check your /home/[username]/.bashrc file and comment out any lines where you have modules loading, have altered your $PATH directory, or have an Anaconda python environment loading.  

This might look like any of these examples:

export PATH="/some/other/directory/: $PATH"

module load python

# >>> conda initialize >>>

# !! Contents within this block are managed by 'conda init' !!

__conda_setup="$('/util/common/python/py27/anaconda-2019.10/bin/conda' 'shell.bash' 'hook' 2> /dev/null)"

if [ $? -eq 0 ]; then

    eval "$__conda_setup"


    if [ -f "/util/common/python/py27/anaconda-2019.10/etc/profile.d/" ]; then

        . "/util/common/python/py27/anaconda-2019.10/etc/profile.d/"


        export PATH="/util/common/python/py27/anaconda-2019.10/bin:$PATH"



unset __conda_setup

# <<< conda initialize <<<

These types of modifications to your environment get loaded every time you start a new shell or launch a desktop on a node.  Often times these changes will break the OnDemand desktop environment.  You should not load these in your .bashrc file but rather once you're in a desktop session, load the modules you need or call them in your Slurm batch script.