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Frequently Asked Questions

We’re here to help, so don’t be afraid to contact our customer support! Here is a list of questions we are asked on a regular basis:

  1. What is Java?
  2. Why do I need Java?
  3. Is Java free to download?
  4. How to install OSCA®?
  5. I want to install OSCA® on my tablet. Is this possible?
  6. The application does not start automatically
  7. Unidentified Developer
  8. Application Error
  9. Invalid or corrupt jar file
  10. Missing Desktop Icon
  11. Citrix Environment
  12. How to uninstall OSCA®?
  13. Activate Debug Output (Java Console)
  14. Could not access the server

What is Java?

Java is a programming language and computing platform first released by Sun Microsystems in 1995. It is the underlying technology that powers state-of-the-art programs including utilities, games, and business applications. Java runs on more than 850 million personal computers worldwide, and on billions of devices worldwide, including mobile and TV devices.


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Why do I need Java?

There are lots of applications and websites that won’t work unless you have Java installed, and more are created every day. Java is fast, secure, and reliable. From laptops to datacenters, game consoles to scientific supercomputers, cell phones to the Internet, Java is everywhere!


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Is Java free to download?

Yes, Java is free to download. Get the latest version here: Java


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How to install OSCA®?

Please follow the steps below to install OSCA®:

Click on the install link we provided to you via email.
A small jlnp file is downloaded to your computer.
Double-click on the file to launch the application and approve the security question.
The test application will solely perform a network and file-system check.
You can remove the software later via the Java Console of your operating system.
Please note:

OSCA® does not need administrator rights for installation.
OSCA® does not need any specific firewall settings.


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I want to install OSCA® on my tablet. Is this possible?

Currently, the tablets with native support are tablets running Microsoft Windows (e.g. Microsoft Surface 2 / Surface 3 Pro).

However, you can still use any given tablet with OSCA®:
Ask your IT to setup a Windows Terminal Server session running an OSCA® instance. By using freely available RDP software, you can connect to the terminal server session and thus using OSCA® on your tablet.

This restrictions applies because OSCA® requires a Java Runtime Environment (JRE) to be installed. Most of today’s tablets do not support this, including Apple’s iPad or any Android tablet. As a consequence, OSCA® cannot be installed and run natively on any of these devices.


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The application does not start automatically

After clicking on the „Install OSCA®“ button, the browser only downloads a JNLP file and does not start the installation process.

In some cases .jnlp files (OSCA®’s installation file) are not assigned to the Java Webstart application. To correct this problem, please do the following:

Download the installation file to your Desktop.
Right click on the downloaded file and select „Open with…“ from the popup menu.
Choose „javaws“ and apply changes.
After double clicking the downloaded jnlp file the installation process should start.


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Unidentified Developer

After downloading the jnlp, it cannot be opened because of the following error message:

In order to allow the installation of the software, you need to follow these steps:

Click on „System Preferences“.
Select „Security and Privacy“.
Select Tab „General“.
If applicable, unlock your settings by clicking on the lock icon on the bottom left side of the dialog.
Apply the below setting.
Close the dialog.

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Application Error

Under certain circumstances, Java may fail to install / start. Please follow the instructions below if you are experiencing the following error message.
During the first installation of OSCA® the following error message is shown.

This error is most likely caused by a disabled file cache of Java. Please follow the steps below to activate it:

  • Open your Windows Control Panel.
  • Search for the Java Entry and click on it.
  • Click on „Settings…“.
  • Ensure that the Tickmark „Keep temporary files on my computer.“ is checked.

Please also ensure that JAVA is using a direct internet connection. This can also be enabled in this dialog:


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Invalid or corrupt jar file

You see this message during or after installation of OSCA®:

Most of the times this error can be resolved by clearing your Java Cache. Please open your Control Panel and double click on the Java icon.
Click on „Settings“.

Click on „Delete files…“.

Tick mark the selected entries and click „OK“.

At this point, try to run OSCA® again. If it runs fine, you do not need to continue.
If not, open up the dialog again, select all entries and click „OK“.

Now try to run OSCA® again. If it runs fine, you do not need to continue.
If not, please try the following setting (untick „Keep temporary files on my computer“ and click „OK“).

Alternatively, you can delete your Java Cache manually. It is located here: C:UsersAppDataLocalLowSunJavaDeployment


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Missing Desktop Icon

If you do not have a desktop (shortcut) icon for OSCA®, you can manually create an icon.
Open your control panel.

Search for Java and double click the icon.

Click on „View…“.

Select the OSCA® application and click the icon marked on the top („Install Shortcuts…“).


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Citrix Environment

OSCA® uses a web technology that use Java Runtime Environment (JRE)/Java. This technology does not necessarily play nicely with Citrix XenApp out of the box. The main problem is the Java cache. It wants to write its cache to:
By default, during a XenApp session nothing ever gets populated past the „username“ part or is vanished after ending a session.
To redirect the cache to another folder, locate and open the following file in a text editor:
Locate or add (if missing) the following line:
in which „absolutePathToNewCacheDir“ is the new path to your cache folder.
Please not the following restrictions:
"" (without quotes) needs to be escaped by "" (without quotes)
":" (without quotes) needs to be escaped by "" (without quotes)

A valid entry could be:
Please ensure that the folder is existing and writable.
The change applies immediately after saving the file. The next Java Webstart application installed on this system will then be consequently installed in the folder.
Oracle is also providing a detailed information page about the deployment configuration: http://docs.oracle.com/javase/7/docs/technotes/guides/jweb/index.html


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How to uninstall OSCA®?

If your OSCA® is not working properly anymore or you simply wish it to uninstall, follow these steps:
Open your control panel.

Search for Java and double click the icon.

Click on „View…“.

Select the OSCA® application and click the icon marked on the top („Remove selected resources…“).


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Activate Debug Output (Java Console)

This is an advanced debug feature intended to be used only by system administrators.
Sometimes, if OSCA® fails to install, it has been proven helpful to activate the Java internal debug console.
To activate the Java console, simply open up the Java Control Panel and activate the following setting:


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Could not access the server

In some cases it has been proven helpful to clear your SSL certificate state.
For this, open up Internet Explorer and open the settings dialog („Internet Options“). Navigate to the „Content“ tab shown below and click on „Clear SSL state“.

At the same time make sure, that under the „Advanced“ tab the entry „Use TLS 1.0“ is checked:

In some cases (i.e. Windows XP) it might be necessary to also deactivate the following options:

  • Use SSL 2.0
  • Use SSL 3.0

It is also required for Windows XP users to have at least Microsoft Internet Explorer 8.0 installed.


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Your question has not been answered? Don’t be afraid to contact our customer support.