java - NoClassDefFoundError in servler logs -

i'm using classes12.jar connection pooling in our application. there screen which, on clicking, redirects error page.

when checked server logs got exception shown below. error coming our db connection manager (paytfdbbase.java).

this class contains getconnection() returns connection object , calls getconndetails() parameters read. these 2 methods listed below.

it used occur once in blue moon , when comes infra team restarts server , issue gone.

but has been occurring more frequently.

i've checked classes12.jar inside web-inf\lib folder.

all other upload screens work going through same connection manager working correctly

 java.lang.noclassdeffounderror:     oracle/jdbc/pool/oracleconnectioncacheimpl  @     com.arch.paytfdbbase.getconndetails(paytfdbbase.java:787)         @     com.arch.paytfdbbase.getconnection(paytfdbbase.java:180)         @     com.reports.client.payliquiduploadjavabean.getrecords(payliquiduploadjavabean.java:72)         @     jsp_servlet._core.__payliquiduploadfiles._jspservice(__payliquiduploadfiles.java:334)         @ weblogic.servlet.jsp.jspbase.service(jspbase.java:34)    @     weblogic.servlet.internal.stubsecurityhelper$servletserviceaction.run(stubsecurityhelper.java:227)         @     weblogic.servlet.internal.stubsecurityhelper.invokeservlet(stubsecurityhelper.java:125)         @     weblogic.servlet.internal.servletstubimpl.execute(servletstubimpl.java:301)         @     weblogic.servlet.internal.servletstubimpl.execute(servletstubimpl.java:184)         @     weblogic.servlet.internal.webappservletcontext$servletinvocationaction.wraprun(webappservletcontext.java:3732)         @     weblogic.servlet.internal.webappservletcontext$servletinvocationaction.run(webappservletcontext.java:3696)         @     weblogic.security.acl.internal.authenticatedsubject.doas(authenticatedsubject.java:321)         @     weblogic.security.service.securitymanager.runas(securitymanager.java:120)         @     weblogic.servlet.internal.webappservletcontext.securedexecute(webappservletcontext.java:2273)         @     weblogic.servlet.internal.webappservletcontext.execute(webappservletcontext.java:2179)         @     weblogic.servlet.internal.servletrequestimpl.run(servletrequestimpl.java:1490)         @ weblogic.work.executethread.execute(executethread.java:256)  @     weblogic.work.executethread.run(executethread.java:221) 

here connection manager class method used getting connection object.

protected connection getconnection() {     if(con == null || con.isclosed())     {         con = getconndetails();         con.setautocommit(false);     }     return con;     sqlexception se;     se;     printit((new stringbuilder("sqlexception in getconnection() :")).append(se).tostring());     return con; } protected connection getconndetails() {     try     {         initialcontext ic = new initialcontext();         datasource ds = (datasource)ic.lookup("jdbc/oraclecoreds");         con = ds.getconnection();     }     catch(exception exception) { }     if(con != null)         break missing_block_label_264;     boolean data1;     if(encriptflag.equalsignorecase("y"))         data1 = getencrypdata();     else         data1 = getpropdata();     try     {         cpds = new oracleconnectionpooldatasource();         cpds.setdrivertype("thin");         cpds.setnetworkprotocol("tcp");         cpds.setservername(mcname);         cpds.setdatabasename(sid);         cpds.setportnumber(integer.parseint(port));         cpds.setuser(username);         cpds.setpassword(pwd);         ocacheimpl = new oracleconnectioncacheimpl(cpds);         ocacheimpl.setmaxlimit(8);         ocacheimpl.setminlimit(1);         ocacheimpl.setcachescheme(1);     }     catch(sqlexception sqlex)     {         printit((new stringbuilder("paytfdbbase  sqlexception getconndetails():")).append(sqlex).tostring());     }     catch(exception ex)     {         printit((new stringbuilder(":2:paytfdbbase  exception getconndetails():")).append(ex).tostring());     }     return ocacheimpl.getconnection();     exception sqlex;     sqlex;     printit((new stringbuilder("paytfdbbase exception in connection():")).append(sqlex).tostring());     return con; }