I have heard this in more than one conversation: my advisor doesn’t know my topic well enough to teach me anything. I understand the feeling. It usually comes from someone working hard on a problem, who finds that the person meant to help cannot follow all of it.
But I have come to see it differently. I think the word learn means something different in a PhD than it does in a class. Once that becomes clear, the relationship gets much easier.
Your advisor is not expected to know your problem
Think about what your professor’s own PhD looked like. It went deep into one thesis, one set of questions, one small corner of a field. A postdoc goes deeper still. That depth is the point of the degree. The price of it is breadth.
Your work sits somewhere else. If your advisor is a junior professor, their thesis is recent, so we expect it to overlap with yours. Often it does not. Even when the topics are close, the tools you use may be tools you picked up and they did not. So it makes sense to me that an advisor cannot follow every step, and cannot tell you whether the derivation you spent last week on is right.
I do not see that as a weakness. In a group that is working well, it means the student has gone somewhere the advisor has not. That is the goal.
What the student can do
Four things, and I think they are all on the student’s side.
Accept the situation. If you are waiting for someone to check your work line by line, you will wait a long time. Most of the frustration in that wait is something we do to ourselves. It is a much calmer place to work from once you stop expecting it.
Ask questions your advisor can answer. This is the part I would most want to pass on. It is a small change in wording, and it changes what you get back.
Instead of:
Is A correct?
try:
To do A, I did B. Does this approach make sense?
The first asks for a verdict. It asks someone to judge technical details they may not know as well as you do, so the honest answer is I’m not sure, and you leave with nothing. The second asks about direction. Is this a reasonable way to attack the problem? Has this route worked before? Is there a cheaper one? Is this even the right problem to work on?
Those are questions about research taste, and research taste is the thing your advisor has more of than you do. It also travels. Technical detail belongs to one problem; a sense of what is worth doing works everywhere.
Ask for that often, and the well turns out to be deeper than it looked.
Listen to the comments that sting. Sometimes the comment you get back sounds harsh. It is easy to hear it as an attack on work you have spent months on. I would read it another way. Those are usually the same comments a reviewer would write. Your advisor is a peer, and often one of the people who reviews work like yours. They are giving you the review before you submit instead of after. That is a much cheaper order to get it in.
So answering those comments carefully is not politeness. It is the same work you would have to do later anyway, done earlier and for less.
Remember what the degree is. A PhD is, by definition, learning to do research on your own. It is not learning a subject. You can do that from papers, and you will. Your advisor is not there to be a senior engineer on your project. They are there to bring you to the point where you can carry a research problem by yourself: pick it, frame it, judge whether it is going anywhere, and know when to stop.
Against that, an advisor who does not share your technical depth is not a problem to solve. It is close to what the arrangement was for.
What this makes possible
None of this means expecting less from your advisor. It means asking for the right thing. In my experience it makes for a much better relationship.
You stop coming to meetings with a list of things to be checked. You start coming with a position: here is what I tried, here is why, here is where I think it goes, and here is where I want to be told I am wrong about the direction.
Your advisor gets to do the thing they are good at. You get to own the work. And you leave with what the degree was for, which was never a set of answers.