the request doesn't contain a multipart/form-data or multipart/mixed stream, content type header is application/x-www-form-urlencoded;charset=UTF-8

the request doesn't contain a multipart/form-data or multipart/mixed stream, content type header is application/x-www-form-urlencoded;charset=UTF-8

This exception  appears when you want to make upload on your from.

To resolve this problem you must add in your commnadbutton this attribute ajax="false".

and enctype="multipart/form-data" on your form.
Like this:
<h:form enctype="multipart/form-data">

gradle dsl method not found 'android()'

gradle dsl method not found 'android()':
This error appears if you run your project with anthoer Android studio. 

In fact Android Studio incorrectly adds the android() method in the top-level build.gradle file.

So to resolve this problem you have just to delete this code and make rebuild to this your project.

rg.springframework.orm.hibernate3.HibernateOptimisticLockingFailureException: Batch update returned unexpected row count from update

rg.springframework.orm.hibernate3.HibernateOptimisticLockingFailureException: 

Batch update returned unexpected row count from update

This problem appears if we use hibernate and we want to add an object on 

the database.

This exception occurs,when we want to add the value of a primary key and we

 make the column on the table autoincrement.

So to get rid of this exception we must remove autoincrement from the database at 

this column or we have to remove the addition of this value 

 from the code or from the form.

org.apache.http.conn.HttpHostConnectException: Connection to http://10.0.2.2:80 refused

 org.apache.http.conn.HttpHostConnectException: Connection to http://10.0.2.2:80 refused

This exception occurs when you want to invoke from your emulator an url from apache ,using for example wamp or easyphp.
To resolve it you must add 10.0.2.2 to be allowed on the file of configuration of apache server.
So go to Apache httpd.conf (located in Apache folder): and search for

Order Deny,Allow
Deny from all
Allow from 127.0.0.1

and check if the second line is Deny, if it is then change it to:

Allow from all

FailOnMissingWebXml

FailOnMissingWebXml error when validating pom.xml in Eclipse

this exception occurs on a maven project .

To resolve it you must add this :

  <properties>

 <failOnMissingWebXml>false</failOnMissingWebXml>

  </properties>

on your pom.xml