I've added the target and the first issue is resolved.
Now I'm getting the following error,
There is no active transaction. This error is usually caused by custom plug-ins that ignore errors from service calls and continue processing.
<soap:Envelope xmlns:soap='http://schemas.xmlsoap.org/soap/envelope/'>
<soap:Body>
<Execute xmlns='http://schemas.microsoft.com/xrm/2011/Contracts/Services' xmlns:i='http://www.w3.org/2001/XMLSchema-instance'>
<request xmlns:a='http://schemas.microsoft.com/xrm/2011/Contracts'>
<a:Parameters xmlns:b='http://schemas.datacontract.org/2004/07/System.Collections.Generic'>
<a:KeyValuePairOfstringanyType>
<b:key>Target</b:key>
<b:value i:type='a:EntityReference'>
<a:Id>{E34CF60B-BBB2-E711-80E8-00155D782518}</a:Id>
<a:LogicalName>account</a:LogicalName>
<a:Name i:nil='true' />
</b:value>
</a:KeyValuePairOfstringanyType>
</a:Parameters>
<a:RequestId i:nil='true' />
<a:RequestName>test_action</a:RequestName>
</request>
</Execute>
</soap:Body>
</soap:Envelope>
<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/">
<s:Body>
<s:Fault>
<faultcode>s:Client</faultcode>
<faultstring xml:lang="en-US">There is no active transaction. This error is usually caused by custom plug-ins that ignore errors from service calls and continue processing.</faultstring>
<detail>
<OrganizationServiceFault xmlns="http://schemas.microsoft.com/xrm/2011/Contracts" xmlns:i="http://www.w3.org/2001/XMLSchema-instance">
<ErrorCode>-2147220911</ErrorCode>
<ErrorDetails xmlns:a="http://schemas.datacontract.org/2004/07/System.Collections.Generic"/>
<Message>There is no active transaction. This error is usually caused by custom plug-ins that ignore errors from service calls and continue processing.</Message>
<Timestamp>2017-10-16T22:18:06.7861343Z</Timestamp>
<InnerFault i:nil="true"/>
<TraceText i:nil="true"/>
</OrganizationServiceFault>
</detail>
</s:Fault>
</s:Body>
</s:Envelope>
In spite of the error, the action is executed as a background process and it's successful.