java.lang.NullPointerException when try to attach file with non-Latin characters

Step to Reproduce

1. Go to a Confluence page.
2. Click Tools >> Attachment
3. Click Choose File button
4. Attach file with the name 'İ ' ( use the İ.txt attached in this ticket)
5. The following error will appear in the browser and the atlassian-confluence.log file.

   java.lang.NullPointerException
   at com.atlassian.confluence.pages.actions.beans.AttachmentStorer.attachFiles(AttachmentStorer.java:64)
   Stack Trace:[hide]
   
   java.lang.NullPointerException
   at com.atlassian.confluence.pages.actions.beans.AttachmentStorer.attachFiles(AttachmentStorer.java:64)
   at com.atlassian.confluence.pages.actions.AbstractViewAttachmentsAction.execute(AbstractViewAttachmentsAction.java:104)
   at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:168)
   at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:35)
   at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
   at 
   

Workaround

Applicable for other non-latin languages except for İ Turkish character

1. Ensure your database collation settings are able to handle international strings.
   Refer to this comment for a PostgreSQL fix
2. Refer to this link for more information