I created a dedicated bug on our SOAP API for that: bugs #3582

While resuming my work on this issue, I have found another problem:

AxisFault
faultCode: 0
faultSubcode:
faultString: Permission Denied: You are not granted sufficient permission to perform this operation.
faultActor:
faultNode:
faultDetail:
{http://xml.apache.org/axis/}stackTrace: Permission Denied: You are not granted sufficient permission to perform this operation.
at org.tuleap.mylyn.task.internal.core.wsdl.soap.v2.TuleapTrackerV5APIBindingStub.getTrackerStructure(TuleapTrackerV5APIBindingStub.java:1080)

Since it seems that some (administrative?) rights are still required by Tuleap to retrieve the description of the tracker (semantic, workflow). Since the server is sending us this error message, we don't have the necessary information to render correctly the content of the user interface in the Mylyn editor. With this almost empty description (by judging the state of the editor), I think that clicking on the submit button of the editor would send the value that we have (nothing) for all the fields of the bug so, it would reset all the fields of the artifact.

In the end, it is quite similar to this previous issue (https://tuleap.net/plugins/tracker/?aid=2159):
"During the steps 1 to 4, everything is working nicely and we can retrieve the name of the group, the name of the tracker, the list of the fields etc. When we are running the step n°5, to retrieve the information about the semantic and the workflow of the tracker, the error appears. [...] Ultimately, since the SOAP API may even be used by unregistered users, should we modify something special on our tracker to give them the rights necessary to manipulate the tracker?"

After more investigation, the problem was coming from an outdated password (I didn't know that this mechanism was in place). My password was considered outdated by Tuleap on tuleap.net so it seems that the call to login returned something odd. Changing the password fixed the issue but maybe returning an error message from the server stating that the password is oudated would be more "user friendly". With an invalid username or password, an error message is returned saying "begaudeaus : Invalid Password Or User Name".

I have started to investigate this issue, right now, I came accross this error message while trying to login on "https://tuleap.net/plugins/tracker/?group_id=101" (the tuleap projet on http://tuleap.net).

AxisFault
faultCode: {http://schemas.xmlsoap.org/soap/envelope/}Server.userException
faultSubcode:
faultString: org.xml.sax.SAXException: Processing instructions are not allowed within SOAP messages
faultActor:
faultNode:
faultDetail:
{http://xml.apache.org/axis/}stackTrace:org.xml.sax.SAXException: Processing instructions are not allowed within SOAP messages

This response is received for a call to login (1). The same call to login (2) is working without any issues on demo.tuleap.net. I have tested it on demo.tuleap.net on three different projects (138, 140 and 141). Did something change in the answer provided by a call to login between the version 6.0.99.8 (demo.tuleap.net) and the version 6.0.99.12 (tuleap.net)? From what I have seen on various forum about this error message, it looks as if the server was returning a HTML page as an answer instead of the session object.

1: https://tuleap.net/soap/wsdl#op.id1166994261184
2: https://demo.tuleap.net/soap/wsdl#op.id393883902986