Why dissertation guidelines and project plan do not work?

New to dissertation project works, some students can get nervous when they find that they cannot meet their commited dissertation proposal objectives nor their dissertation project milestones, etc... I think there are several major reasons for that and the situation facing the students may not be that scaring:

The reasons can be:

1. Fundamentally, your project proposals are unclear about what you intend to do. Nevertheless, you have submitted your dissertation proposals to meet administration deadlines. In this case, you still need to finish your "unfinished" tasks to write up a dissertation proposal.
2. As you become more knowledgeable with your topic areas, you refine your project objectives and research design, leading to changes in your project plans. This is a very legitimate reason to revise your dissertation project plans.
3. In a real-world dynamic settings, many things can happen that require you to respond by revising your dissertation project plans: e.g. changes in the external environment facing your client system leads to changes in their prioritiy of concerns. Your original project objectives may become much less interesting to your clients now; another example is that the client gatekeeper has left the company you are studying and now, you have difficulties to access the client system.
4. As you make progress in your investigation in a client system, you uncover new facts that prompt you to revise your investigation strategy.
5. Finally, a dissertation project plan is a plan, you may not be able to meet your project plan commitment due to estimate errors on time and efforts required.

There may be other more personal reasons that affect your dissertation project progress, e.g. suddenly you need to get married, etc..

After consulting with your dissertation supervisor, you should be able to revise your dissertation plan; in most cases, such changes in dissertation project plans are legitimate.

However, if you want to do a fundamenally new topic because you now feel that your original dissertation proposals that have been approved and marked, you do have a problem. At least, you will be required to prepare a new dissertation proposal for assessment again. In this case, you need to accept the consequences of scrapping your original proposals; in this case, all the other people that support your dissertation works in various roles have extra works to do.