What are the 3 main reasons for project failing, and how to avoid it?

There are many reasons for failure of projects. Main reasons for failure differ from project to project but some common reasons are mentioned below.

1.    Poor leadership at any level

2.    Inadequately-trained project managers

3.    Poor planning and/or inadequate process

4.    Inaccurate cost estimation

5.    Inefficient way to document and track progress

6.    Failure to set expectations and manage them

7.    Lack of communication at any level

8.    Culture or ethical misalignment

9.    Competing priorities

10.   Disregard of project warning signs

from my experience, i can say Low experience of project staff considers as one of the main factors along with other factors such as Leader professional skills and vague goals or requirements of the project itself.

for any Project, the requirements, and Goals should be very clear from all parties in order to get the mentioned value of the project, anyhow I believe tight plan base on timeframe will lead to a successful project by more than 80%.

Communication (Transparency)- Poor Communication Skills or Poor Communication Plan are a major reason for the Failure of the Project. It may be between the Project Sponsor to Project Team or Business to Project Sponsor. It can be any reason.

Risk Identification & Mitigation (Adaptation) - It is very much necessary to identify risks & develop a mitigation plan accordingly. The development team needs to be adaptive to incorporate these changes within a given boundary of parameters.

Monitoring & Controlling (Inspection) - If the project is not monitored properly at given intervals, the project is bound to fail. We need to have checks and balances at various levels to ensure quality. Whether it is UNIT Testing, Peer to Peer Review, System Violations, Architect Review, QA Review, Sanity Testing or UAT.

The three pillars of SCRUM namely Transparency, Adaptation and Inspection should be intact to make sure that Project succeeds.

we have a lot of reasons behind failure of any project but from my respective i can say : 

1- project manager (if he hasn't skills of art and science to manage his project in light of the project constrains. 

2- Stakeholders: who is doing the work ? if no effective and efficient cooperation to get this project successfully deployed ..

3- baseline ( scope- schedule- cost ) : if these baselines are not clear to meet and measure where you are, how do you know how is your project going on ? ..

i have more and more but from my respective these  are major points to get your success or failed .