The following are some situations that cannot be upgraded:

1. Some institutions: Some institutions may only offer courses at the junior college level, but not at the undergraduate level. These schools often only provide three-year college education, and there is no option to upgrade to undergraduate courses.

2. Specific vocational education: Some vocational education institutions, technical schools or vocational training schools provide short-term training courses for specific vocational skills. Generally, these institutions do not provide educational channels for upgrading from junior college to undergraduate college.

3. Higher vocational colleges: Higher vocational colleges are established to cultivate students who are more inclined to vocational skills. Although some vocational colleges offer four-year university degree courses, not all vocational colleges offer the opportunity to upgrade to undergraduate courses.

4. Degree type restriction: In some countries or regions, some university graduates can only obtain college diplomas or certificates, but not undergraduate degrees. This means that even if they want to continue their studies, they can't enter the undergraduate stage by upgrading to undergraduate.

Common methods of upgrading from university to undergraduate:

1, high-level athletes walk: Some colleges and universities provide high-level athletes walk policies for junior college students with outstanding sports achievements, allowing them to skip the undergraduate selection examination and directly enter the undergraduate course.

2. Unified examination: Some colleges and universities admit undergraduates through unified examinations (such as the college entrance examination), and college graduates can take the college entrance examination and apply for undergraduate admission qualifications through the results of the college entrance examination.

3. College entrance examination: Some colleges and universities will organize college graduates to take the college entrance examination. After passing the exam, you can go directly to the undergraduate course. This kind of examination is usually aimed at college graduates with practical work experience.

4. Changing majors: Some colleges and universities allow college graduates to enter the undergraduate stage by changing majors and transfer to corresponding majors for undergraduate study.

Requirements for undergraduate courses:

1. Education requirements: General applicants need to hold a nationally recognized college diploma or equivalent.

2.GPA/ academic performance requirements: Colleges and universities may require applicants to achieve certain academic performance at the specialist level, usually with GPA or credit scores as reference.

3. Professional requirements: Some universities and majors may have specific requirements for the majors studied by applicants, such as related majors or related majors.

4. Personal quality requirements: colleges and universities may comprehensively evaluate the applicant's comprehensive quality, including but not limited to moral quality, comprehensive quality, social practice, scientific and technological innovation, etc.

5. Related examinations: Some colleges or majors may require applicants to take undergraduate examinations, which may include knowledge tests and comprehensive quality evaluation of related disciplines.