Server throws "SERVER ERRO 500" at times about kaptcha HOT 3 CLOSED

More details please. What is in your logs? Stack trace? Server configuration?

I've NEVER seen Kaptcha throw an error in about 2 years of use, so my guess is 
that you are doing something 
wrong that has nothing to do with Kaptcha. 

Marking as invalid until you respond with more information that would be of any 
use to me because what you 
have sent so far is pretty much a waste of my time.

Hi,
i'm also experiencing a ploblem like that described. I run BEA weblogic 10 
(solaris).
It seems that when the problem occurs, the server can't respond anymore to 
requests
for captcha gifs and the strange thing is that after uninstall/delete/re-deploy 
the
webapp that uses kaptcha, the problem is still there!!! (also after 
reinitializing
BEA instance). So i guess it is something dealing more with OS than java/bea.
Follows 2 exceptions i have on my logs when the problem appears.
Any help in understanding the problem is welcome!
Francesco
===== 
Root cause of ServletException.
java.lang.InternalError: Can't connect to X11 window server using 
'localhost:10.0' as
the value of the DISPLAY variable.
    at sun.awt.X11GraphicsEnvironment.initDisplay(Native Method)
    at sun.awt.X11GraphicsEnvironment.access$000(X11GraphicsEnvironment.java:53)
    at sun.awt.X11GraphicsEnvironment$1.run(X11GraphicsEnvironment.java:142)
    at java.security.AccessController.doPrivileged(Native Method)
    at sun.awt.X11GraphicsEnvironment.<clinit>(X11GraphicsEnvironment.java:131)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:164)
    at java.awt.GraphicsEnvironment.getLocalGraphicsEnvironment(GraphicsEnvironment.java:68)
    at java.awt.image.BufferedImage.createGraphics(BufferedImage.java:1141)
    at
com.google.code.kaptcha.text.impl.DefaultWordRenderer.renderWord(DefaultWordRend
erer.java:39)
    at com.google.code.kaptcha.impl.DefaultKaptcha.createImage(DefaultKaptcha.java:43)
    at com.google.code.kaptcha.servlet.KaptchaServlet.doGet(KaptchaServlet.java:84)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:707)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
    at
weblogic.servlet.internal.StubSecurityHelper$ServletServiceAction.run(StubSecuri
tyHelper.java:226)
    at
weblogic.servlet.internal.StubSecurityHelper.invokeServlet(StubSecurityHelper.ja
va:124)
    at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:283)
    at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:175)
    at
weblogic.servlet.internal.RequestDispatcherImpl.invokeServlet(RequestDispatcherI
mpl.java:528)
    at
weblogic.servlet.internal.RequestDispatcherImpl.forward(RequestDispatcherImpl.ja
va:261)
    at it.amuser.webClick2Call.F2TServlet.processRequest(F2TServlet.java:108)
    at it.amuser.webClick2Call.F2TServlet.doGet(F2TServlet.java:531)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:707)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
    at
weblogic.servlet.internal.StubSecurityHelper$ServletServiceAction.run(StubSecuri
tyHelper.java:226)
    at
weblogic.servlet.internal.StubSecurityHelper.invokeServlet(StubSecurityHelper.ja
va:124)
    at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:283)
    at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:175)
    at
weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.run(WebAp
pServletContext.java:3395)
    at
weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.ja
va:321)
    at weblogic.security.service.SecurityManager.runAs(Unknown Source)
    at
weblogic.servlet.internal.WebAppServletContext.securedExecute(WebAppServletConte
xt.java:2140)
    at
weblogic.servlet.internal.WebAppServletContext.execute(WebAppServletContext.java
:2046)
    at weblogic.servlet.internal.ServletRequestImpl.run(ServletRequestImpl.java:1366)
    at weblogic.work.ExecuteThread.execute(ExecuteThread.java:200)
    at weblogic.work.ExecuteThread.run(ExecuteThread.java:172)
> 

Root cause of ServletException.
java.lang.NoClassDefFoundError
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:164)
    at java.awt.GraphicsEnvironment.getLocalGraphicsEnvironment(GraphicsEnvironment.java:68)
    at java.awt.image.BufferedImage.createGraphics(BufferedImage.java:1141)
    at
com.google.code.kaptcha.text.impl.DefaultWordRenderer.renderWord(DefaultWordRend
erer.java:39)
    at com.google.code.kaptcha.impl.DefaultKaptcha.createImage(DefaultKaptcha.java:43)
    at com.google.code.kaptcha.servlet.KaptchaServlet.doGet(KaptchaServlet.java:84)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:707)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
    at
weblogic.servlet.internal.StubSecurityHelper$ServletServiceAction.run(StubSecuri
tyHelper.java:226)
    at
weblogic.servlet.internal.StubSecurityHelper.invokeServlet(StubSecurityHelper.ja
va:124)
    at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:283)
    at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:175)
    at
weblogic.servlet.internal.RequestDispatcherImpl.invokeServlet(RequestDispatcherI
mpl.java:528)
    at
weblogic.servlet.internal.RequestDispatcherImpl.forward(RequestDispatcherImpl.ja
va:261)
    at it.amuser.webClick2Call.F2TServlet.processRequest(F2TServlet.java:108)
    at it.amuser.webClick2Call.F2TServlet.doGet(F2TServlet.java:531)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:707)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
    at
weblogic.servlet.internal.StubSecurityHelper$ServletServiceAction.run(StubSecuri
tyHelper.java:226)
    at
weblogic.servlet.internal.StubSecurityHelper.invokeServlet(StubSecurityHelper.ja
va:124)
    at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:283)
    at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:175)
    at
weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.run(WebAp
pServletContext.java:3395)
    at
weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.ja
va:321)
    at weblogic.security.service.SecurityManager.runAs(Unknown Source)
    at
weblogic.servlet.internal.WebAppServletContext.securedExecute(WebAppServletConte
xt.java:2140)
    at
weblogic.servlet.internal.WebAppServletContext.execute(WebAppServletContext.java
:2046)
    at weblogic.servlet.internal.ServletRequestImpl.run(ServletRequestImpl.java:1366)
    at weblogic.work.ExecuteThread.execute(ExecuteThread.java:200)
    at weblogic.work.ExecuteThread.run(ExecuteThread.java:172)
> 

This has nothing to do with Kaptcha and everything to do with your os/java 
install. Did 
you try asking google for a solution?

http://www.google.com/search?
client=safari&rls=en&q=%22Can't+connect+to+X11+window+server+using+'localhost:
10.0'%22&ie=UTF-8&oe=UTF-8