ClobStringType requires active transaction sync exception

As a result of the exception below, the edited pages can not be saved. Suggestions are very welcome...
Stephan

<[ServletContext(id=18982466,name=confluence,context-path=/confluence)] Servlet failed with Exception
java.lang.IllegalStateException: ClobStringType requires active transaction synchronization
at com.atlassian.confluence.util.ConfluenceClobStringType.nullSafeSet(ConfluenceClobStringType.java:51)
at net.sf.hibernate.type.CustomType.nullSafeSet(CustomType.java:118)
at net.sf.hibernate.persister.EntityPersister.dehydrate(EntityPersister.java:393)
at net.sf.hibernate.persister.EntityPersister.insert(EntityPersister.java:466)
at net.sf.hibernate.persister.EntityPersister.insert(EntityPersister.java:442)
at net.sf.hibernate.impl.ScheduledInsertion.execute(ScheduledInsertion.j
ava:29)
at net.sf.hibernate.impl.SessionImpl.executeAl(SessionImpl.java:2382)
at net.sf.hibernate.impl.SessionImpl.execute(SessionImpl.java:2335)
at net.sf.hibernate.impl.SessionImpl.flush(SessionImpl.java:2204)
at bucket.custom.FlushingSpringSessionInViewFilter.closeSession(Flushing SpringSessionInViewFilter.java:39)
at org.springframework.orm.hibernate.support.OpenSessionInViewFilter.doF
ilterInternal(OpenSessionInViewFilter.java:122)
at bucket.custom.FlushingSpringSessionInViewFilter.doFilterInternal(FlushingSpringSessionInViewFilter.java:30)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:73)
at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:27)
at com.atlassian.util.profiling.filters.ProfilingFilter.doFilter(ProfilingFilter.java:132)
at com.atlassian.confluence.util.error.ProfilingAndErrorFilter.doFilter(
ProfilingAndErrorFilter.java:25)
at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:27)
at com.atlassian.util.profiling.filters.ProfilingFilter.doFilter(Profili
ngFilter.java:132)
at com.atlassian.confluence.util.error.ProfilingAndErrorFilter.doFilter(
ProfilingAndErrorFilter.java:25)
at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:27)
at com.atlassian.core.filters.AbstractEncodingFilter.doFilter(AbstractEncodingFilter.java:38)
at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:27)
at weblogic.servlet.internal.WebAppServletContext$ServletInvocationActio
n.run(WebAppServletContext.java:6356)
at weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.java:317)
at weblogic.security.service.SecurityManager.runAs(SecurityManager.java:118)
at weblogic.servlet.internal.WebAppServletContext.invokeServlet(WebAppSe
rvletContext.java:3635)
at weblogic.servlet.internal.ServletRequestImpl.execute(ServletRequestImpl.java:2585)
at weblogic.kernel.ExecuteThread.execute(ExecuteThread.java:197)
at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:170)