NoClassDefFoundError – com/jacob/com/ComFailException

NoClassDefFoundError – com/jacob/com/ComFailException

The reason for this error is because the Java cache may be interfering with properly finding the Java classes associated with jacob.jar. Clearing the Java cache should fix the problem:

1. Open up the Control Panel on the end user’s PC
2. Go to All Control Panel Items and click “Java”
3. With the General tab highlighted in the Java Control Panel, click “Settings…”
4. Click “Delete Files…” to prepare to delete all objects in the Java cache. 
5. In the new pop-up window, have only the following selected and click “OK”:
   • Trace and Log Files
   • Cached Applications and Applets
   • 
6. After the window closes, click “OK” twice to close all windows in the Java Control Panel.

Install and configure SFTP/FTP server in Oracle Linux

Step 1: We will use localhost for our machine to setup ftp server.

Step 2: Install vsftpd (very secure FTP daemon) package.

yum install -y vsftpd

Step 3: Start FTP Server when system on.

systemctl enable vsftpd.service

Step 4: Checking the status of ftp server

systemctl status vsftpd.service

Step 5: Configure vsftpd package. We will edit
/etc/vsftpd/vsftpd.conf

Change the line which contain anonymous_enable=NO to anonymous_enable=YES
This will give permit any one to access FTP server with authentication.
Change the following to YES
local_enable=YES
write_enable=YES

Step 6: Start FTP Server
systemctl start vsftpd.service

Step 7: Install FTP Client
yum install -y lftpd

Step 8: Connect ftp to localhost
lftp localhost

Signing JAR Files

$ORACLE_HOME/jdk/bin/jarsigner -keystore .keystore_myapp -storepass abcd1234 $ORACLE_HOME/forms/java/jacob.jar myapp

Enter keystore password:  mypassword
What is your first and last name?
  [Unknown]:  Concept
What is the name of your organizational unit?
  [Unknown]:  My Concept Department
What is the name of your organization?
  [Unknown]:  My Concept Company
What is the name of your City or Locality?
  [Unknown]:  My Concept City
What is the name of your State or Province?
  [Unknown]:  My Concept State
What is the two-letter country code for this unit?
  [Unknown]:  AE
Is CN=Concept, OU=My Concept Department, O=My Concept Company, L=My Concept City, ST=My Concept State, C=AE correct?
  [no]:  yes

Enter key password for
        (RETURN if same as keystore password):


/u01/app/oracle/product/12.2.1.3/oracle_common/jdk/bin/jarsigner -keystore .keystore_myapp -storepass abcd1234 $ORACLE_HOME/forms/java/jacob.jar myapp

VirtualBox Host-Only Static IP

To create a host-only connection in VirtualBox, start by opening the preferences in VirtualBox. Go to the "Network" tab, and addd a Host-only Network. 

To get the static IP address working temporarily, access the termainal on the client, and enter the following to assign a static IP to eth1. (I'm assuming 192.168.56.101 because that's VirtualBox's default. Make sure it matches the IP for your host-only adapter.)

ifconfig eth1 192.168.56.101 netmask 255.255.255.0 up