=== HTTPSampler to HTTPSampler2 convertion ===

If the testcase was created with an old version, load it into 2.1.1 and save it.
Edit the testcase and replace the following:

Old
===
<HTTPSampler>
<stringProp name="TestElement.test_class">
org.apache.jmeter.protocol.http.sampler.HTTPSampler</stringProp>
<stringProp name="TestElement.gui_class">
org.apache.jmeter.protocol.http.control.gui.HttpTestSampleGui</stringProp>
</HTTPSampler>

New
===
<HTTPSampler2>
<stringProp name="TestElement.test_class">
org.apache.jmeter.protocol.http.sampler.HTTPSampler2</stringProp>
<stringProp name="TestElement.gui_class">
org.apache.jmeter.protocol.http.control.gui.HttpTestSampleGui2</stringProp>
</HTTPSampler2>