The EINVALIDTAGNAME error occurs when npm encounters tag names or version specifiers containing characters that encodeURIComponent encodes (like @, ^, >, =). This typically happens with malformed version specifiers in dependencies.
This error means npm encountered a tag name or version specifier that contains characters not allowed in package tags. Npm validates tag names by checking if they contain any characters that JavaScript's encodeURIComponent() function would encode. Characters like @, ^, >=, &, +, $, #, and / are encoded by encodeURIComponent(), making them invalid in npm tags. The only characters allowed in tags are alphanumerics plus -_.!~*'(). This validation prevents malformed dependencies from being installed and protects against corruption in your dependency tree.
Open your package.json file and look for version specifiers with unusual syntax. Invalid patterns include combining multiple range operators like '>=^'.
// Invalid:
{
"dependencies": {
"react": ">=^16.0.0"
}
}
// Correct:
{
"dependencies": {
"react": "^16.0.0"
}
}For combined ranges, use proper syntax with spaces:
{
"dependencies": {
"package": ">=1.0.0 <2.0.0"
}
}Remove the node_modules directory and package-lock.json file to eliminate any cached corrupted dependency data:
rm -rf node_modules package-lock.json
# On Windows:
rmdir /s /q node_modules
del package-lock.jsonThis forces npm to re-resolve all dependencies from scratch.
Use npm ci (clean install) instead of npm install. npm ci is more strict and sometimes succeeds when npm install fails:
npm ciIf npm ci succeeds, the issue is with npm's resolution logic rather than your dependencies.
If you're sure your dependencies are correct but npm validation is causing issues, use the --legacy-peer-deps flag:
npm install --legacy-peer-depsThis flag tells npm to ignore peer dependency validation, which can help when dealing with packages that have loose peer dependency specifications.
The error validation happens because npm uses encodeURIComponent() internally to process tag names. Characters that this function encodes include: , / ? : @ & = + $ # and others. Only alphanumerics and -_.!~*'() are allowed. Some older npm packages in the registry have malformed peer dependency specifications that haven't been fixed by maintainers. If you encounter this with a third-party package, you may need to use --legacy-peer-deps or switch to yarn which has more lenient validation.
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