No, but it creates a problem worth fixing
Changing your name by deed poll does not invalidate a will written under your old name. The will stays legally effective and your executors can still act on it.
What changes is the paperwork. The will names one person and your death certificate names another, so someone has to prove those are the same person before your estate can be settled.
One important exception: marriage
If your name changed because you got married or entered a civil partnership, the name change is not the real issue. Getting married revokes your existing will in England and Wales, unless that will was written specifically in contemplation of the marriage. That is a far bigger problem than a name mismatch, and it applies whether or not you took your spouse's surname.
If you have married since writing your will, read does marriage cancel my will? and work on the assumption that you need a new one.
What your executors have to deal with
When applying for probate, the Probate Registry checks the identity of the deceased closely. If your legal name at death differs from the name on the will, your executor has to evidence the link, usually by producing the deed poll alongside the grant application.
Banks, pension providers, HMRC and the Land Registry can all ask for the same thing before releasing anything. If the deed poll was lost, or never formally obtained, this gets slow and awkward at the worst possible time for your family.
Your three options
Write a new will in your new name. The cleanest fix. A new will carries a revocation clause cancelling everything before it, so there is no ambiguity and no competing documents left in circulation.
Add a codicil. A codicil is a formal amendment recording the name change. It has to be signed and witnessed with exactly the same formality as the original will. Fine for a small administrative update, though a fresh will removes more doubt for roughly the same effort.
Keep the deed poll with the will. The minimum. It costs nothing and gives your executor the evidence they need. Less tidy than updating the will, and far better than leaving them to work it out.
If a beneficiary or executor changes their name
A gift does not fail because the person named has since changed their name. Courts look at what you intended, not at literal name matching. Where the difference is significant, though, updating the will closes off any argument before it starts.
If you have not changed your name yet
Get the deed poll first, then write the will in your new legal name. Everything is consistent from the start and the mismatch never arises.
With PureWill
A fresh will in your new name takes about 20 minutes for £79, and it includes a revocation clause that cancels your previous will automatically. If your situation is more complicated than a name change, a second marriage with children from a first for example, a solicitor is the better call.
Related reading: When should I update my will?, What is a codicil? and Does marriage cancel my will?
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Is your situation complex? Blended family, overseas property, business interests, or trusts? Please find a qualified solicitor. PureWill is for straightforward estates only.