[Solved] JDownloader don't start anymore

[avalloneandrea]

I have installed JDownloader on my Raspberry Pi. After a reboot, JDownloader give an error on startup:

|---------------------------Headless Information-------------------------------
|	Exception occured
|	Exception occured
|	An unexpected error occured.
|	JDownloader will try to fix this. If this happens again, please contact our support.
|	java.lang.NoClassDefFoundError: org/appwork/utils/net/httpserver/handler/ExtendedHttpRequestHandler
|		at java.lang.ClassLoader.defineClass1(Native Method)
|		at java.lang.ClassLoader.defineClass(ClassLoader.java:760)
|		at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
|		at java.net.URLClassLoader.defineClass(URLClassLoader.java:467)
|		at java.net.URLClassLoader.access$100(URLClassLoader.java:73)
|		at java.net.URLClassLoader$1.run(URLClassLoader.java:368)
|		at java.net.URLClassLoader$1.run(URLClassLoader.java:362)
|		at java.security.AccessController.doPrivileged(Native Method)
|		at java.net.URLClassLoader.findClass(URLClassLoader.java:361)
|		at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
|		at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
|		at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
|		at org.jdownloader.api.RemoteAPIController.<init>(RemoteAPIController.java:315)
|		at org.jdownloader.api.RemoteAPIController.<clinit>(RemoteAPIController.java:116)
|		at jd.SecondLevelLaunch$12$1.run(SecondLevelLaunch.java:881)
|	Caused by: java.lang.ClassNotFoundException: org.appwork.utils.net.httpserver.handler.ExtendedHttpRequestHandler
|		at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
|		at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
|		at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
|		at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
|		... 15 more
|	Press Enter to continue

What does it means? How to resolve?

[Jiaz]

Close JDownloader and delete JDownloader.jar and Core.jar, also the folders 'tmp' and 'update'
Download installer.jdownloader.org/JDownloader.jar and place it in your folder and start JDownloader again.

Do you use systemd to start JDownloader? If so, please show the script

[avalloneandrea]

The procedure solved the problem, thank you!

To be honest, it's not the first time my JDownloader encounter an exception at startup, when it tries to install an update. I usually resolve the problem by deleting Core.jar and restarting JDownloader, but this time something else broke. Do you think disabling automatic updates could be a solution?

Yes I start JDownloader with this systemd script:

[Unit]
Description=JDownloader Daemon
After=network-online.target

[Service]
Type=simple
User=pi
ExecStartPre=-/bin/mv /home/pi/.jdownloader/JDownloader.jar.backup.1 /home/pi/.jdownloader/JDownloader.jar 
ExecStart=/usr/bin/java -Djava.awt.headless=true -jar /home/pi/.jdownloader/JDownloader.jar -norestart
Restart=on-failure
TimeoutStopSec=90

[Install]
WantedBy=multi-user.target

I had to add that ExecStartPre line because sometimes my JDownloader.jar is renamed as JDownloader.jar.backup.1 and the script fails. If you know a better workaround, I'd like to read it

[Jiaz]

Please modify according to this
github.com/OpenMediaVault-Plugin-Developers/openmediavault-jdownloader/blob/master/debian/jdownloader.service

Type and RemainAfterExit are important, else script will break update

DO NOT disable updates fix your script

[avalloneandrea]

I will, thank you!

[Jiaz]

You're welcome

[avalloneandrea]

I just have one minor problem with the new script you gave me: if I manually stop and start JDownloader (with sudo systemctl stop jdownloader && sudo systemctl start jdownloader), the daemon starts but the process never returns (I have to send a ctrl+c in order to regain control of the command line). Is there a way to fix this behavior?

[Jiaz]

modify script to launch JDownloader in background with
...JDownloader.jar &

Also do NOT add '-norestart' . This parameter is only intended for setup

[avalloneandrea]

Unfortunately it's not enough :( This is the modified script:

[Unit]
Description=JDownloader
After=network-online.target

[Service]
User=pi
Group=users
Type=oneshot
ExecStart=/usr/bin/java -Djava.awt.headless=true -jar /home/pi/.jdownloader/JDownloader.jar &
RemainAfterExit=yes
StandardOutput=null

[Install]
WantedBy=multi-user.target

[Jiaz]

ExecStart=/usr/bin/java -Djava.awt.headless=true -jar /home/pi/.jdownloader/JDownloader.jar &

[avalloneandrea]

I'm sorry I didn't notice the previous script was cut because of the size of the window I've copied it from. I have updated the previous post: as you can I see, I'm already using the right command, without success.

[Jiaz]

StandardOutput=null
where does this come from? remove this
ExecStart=/usr/bin/java -Djava.awt.headless=true -jar /home/pi/.jdownloader/JDownloader.jar >/dev/null 2>/dev/null &

[avalloneandrea]

It still doesn't work as expected. It's strange, because if I run

/usr/bin/java -Djava.awt.headless=true -jar /home/pi/.jdownloader/JDownloader.jar >/dev/null 2>/dev/null &

from the command line, it prints the pid and return; however, If i write the same command in the systemd script, and run

sudo systemctl start jdownloader

it never return unless I give a CTRL+C.

[Jiaz]

Can you show the complete systemd script again?

[avalloneandrea]

Sure!

[Unit]
Description=JDownloader Daemon
After=network-online.target

[Service]
User=pi
Group=users
Type=oneshot
ExecStart=/usr/bin/java -Djava.awt.headless=true -jar /home/pi/.jdownloader/JDownloader.jar > /dev/null 2> /dev/null &
RemainAfterExit=yes

[Install]
WantedBy=multi-user.target

[Jiaz]

Did you do?
sudo systemctl daemon-reload
to reload the config files?

Maybe
After=network-online.target
is blocking because the network online is not finished? does this task even start/finish?
I would remove it

[avalloneandrea]

Yes I run a

sudo systemctl daemon-reload

after every edit of the script in order to load the changes.

I don't think

After=network-online.target

is the problem: the network is up, and I'm sure the task start and finish. Also, I have others systemd script with the same line, namely deluge and amule, and they all run smoothly.

[Jiaz]

I'm sorry but I don't know why it blocks for you.
The systemd github.com/OpenMediaVault-Plugin-Developers/openmediavault-jdownloader/blob/master/debian/jdownloader.service
is working fine also yours is working fine

Did you try to remove the after line?

[avalloneandrea]

Yeah I forgot to say that I have tried anyway removing the line, but the outcome is the same :(

[Jiaz]

Can we do a teamviewer Session? contact me at support@jdownloader.org

[Jiaz]

Fixed via teamviewer

Changed 'Type=oneshot' to 'Type=simple'