npm · npm
The message
npm ERR! ERESOLVE unable to resolve dependency tree
What it means
From npm 7 onward peerDependencies ranges are enforced, and this says npm could not find a set of versions that satisfies all of them at once. It is common when the package you are installing has a peer range that excludes the react or typescript version you already have, especially right after a major upgrade. Read the Found: and Could not resolve: lines to see who demands what, then move one of the two to a compatible version — that is the real fix. npm install --legacy-peer-deps installs by ignoring peer ranges entirely, which unblocks you but leaves a tree the packages never agreed on, so the runtime errors from mismatched versions are yours to debug.
The fix
npm install --legacy-peer-deps- Printed by
- npm
- npm
- 20
With npm the cause sits in the first code XXXX line rather than the last six npm ERR! lines, and when the failure comes from the dependency tree or a native build instead of your own code, deleting node_modules and installing again clears about half of them.
Reading an error message
- Read from the first line down. The lower you go the more it is about the tool’s internals; the cause is usually at the top.
- If there is a file and a line number, start there — not the top stack frame, but the topmost line that names a file you wrote.
- Search the message verbatim, but strip your own paths and variable names first; those are what stop the search from matching.
- The same condition is worded differently across tool versions. If results look wrong, add the version number to the query.
- Before pasting a fix, check what it throws away. Some of these cannot be undone.
Common questions
Q. What does “npm ERR! ERESOLVE unable to resolve dependency tree” mean?
From npm 7 onward peerDependencies ranges are enforced, and this says npm could not find a set of versions that satisfies all of them at once. It is common when the package you are installing has a peer range that excludes the react or typescript version you already have, especially right after a major upgrade. Read the Found: and Could not resolve: lines to see who demands what, then move one of the two to a compatible version — that is the real fix. npm install --legacy-peer-deps installs by ignoring peer ranges entirely, which unblocks you but leaves a tree the packages never agreed on, so the runtime errors from mismatched versions are yours to debug.
Q. How do I fix it?
npm install --legacy-peer-deps — before running it, check the explanation above for what this command discards.
Q. Which tool prints this?
npm. It sits under npm, and the message runs to 8 words.