E11000 duplicate key error index in mongodb mongoose

Question

Following is my user schema in user js model -  var userSchema   new mongoose Schema       local            name    type  String            email     type  String  require  true  unique  true            password    type  String  require true               facebook            id               type  String            token            type  String            email            type  String            name             type  String              var User   mongoose model  User  userSchema    module exports   User    This is how I am using it in my controller -   var user   require       models user js      This is how I am saving it in the db -  user   local email    req body email   local password    req body password   save function err  result       if err          res send err       else           console log result           req session user   result          res send   code  200  message   Record inserted successfully                 Error -    name   MongoError   code  11000  err   insertDocument    caused by    11000 E11000 duplicate key error index  mydb users  email 1  dup key      null        I checked the db collection and no such duplicate entry exists  let me know what I am doing wrong    FYI -  req body email and req body password are fetching values   I also checked this post but no help STACK LINK  If I removed completely then it inserts the document  otherwise it throws error  Duplicate  error even I have an entry in the local email

User · Answer

Drop you database  then it will work  You can perform the following steps to drop your database step 1   Go to mongodb installation directory  default dir is  quot C  Program Files MongoDB Server 4 2 bin quot  step 2   Start mongod exe directly or using command prompt and minimize it  step 3   Start mongo exe directly or using command prompt and run the following command  i   use yourDatabaseName  use show databases if you don t remember database name    ii  db dropDatabase    This will remove your database  Now you can insert your data  it won t show error  it will automatically add database and collection

User · Answer

This is because there is already a collection with the same name with configuration  Just remove the collection from your mongodb through mongo shell and try again      db collectionName remove     now run your application it should work

User · Answer

I want to explain the answer solution to this like I am explaining to a 5-year-old   so everyone can understand    I have an app I want people to register with their email password and phone number    In my MongoDB database   I want to identify people uniquely based on both their phone numbers and email - so this means that both the phone number and the email must be unique for every person   However   there is a problem   I have realized that everyone has a phonenumber but not everyone has an email address     Those that don t have an email address have promised me that they will have an email address by next week  But I want them registered anyway  -  so I tell them to proceed registering their phonenumbers as they leave the email-input-field empty    They do so     My database NEEDS an unique email address field - but I have a lot of people with  null  as their email address   So I go to my code and tell my database schema to allow empty null email address fields which I will later fill in with email unique addresses when the people who promised to add their emails to their profiles next week     So its now a win-win for everyone  but you  -     the people register  I am happy to have their data    and my database is happy because it is being used nicely    but what about  you   I am yet to give you the code that made the schema    Here is the code    NOTE   The sparse property in email   is what tells my database to allow null values which will later be filled with unique values     x000D   x000D  var userSchema   new mongoose Schema   x000D    local    x000D      name    type  String    x000D      email     type  String  require  true  index true  unique true sparse true   x000D      password    type  String  require true    x000D       x000D    facebook    x000D      id               type  String    x000D      token            type  String    x000D      email            type  String    x000D      name             type  String   x000D      x000D      x000D   x000D  var User   mongoose model  User  userSchema   x000D   x000D  module exports   User  x000D   x000D   x000D    I hope I have explained it nicely   Happy NodeJS coding   hacking

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Had the same issue I resolved it by removing the unique attribute on the property    Just find another way to validate or check for unique property values for your schema

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The error message is saying that there s already a record with null as the email  In other words  you already have a user without an email address  The relevant documentation for this   If a document does not have a value for the indexed field in a unique index  the index will store a null value for this document  Because of the unique constraint  MongoDB will only permit one document that lacks the indexed field  If there is more than one document without a value for the indexed field or is missing the indexed field  the index build will fail with a duplicate key error  You can combine the unique constraint with the sparse index to filter these null values from the unique index and avoid the error   unique indexes  Sparse indexes only contain entries for documents that have the indexed field  even if the index field contains a null value   In other words  a sparse index is ok with multiple documents all having null values  sparse indexes  From comments  Your error says that the key is named mydb users  email 1 which makes me suspect that you have an index on both users email and users local email  The former being old and unused at the moment   Removing a field from a Mongoose model doesn t affect the database  Check with mydb users getIndexes   if this is the case and manually remove the unwanted index with mydb users dropIndex  lt name gt

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mongoDB Atlas has a indexes tab when under their collections tab that allows you to view and delete any index you do not want

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Check collection indexes   I had that issue due to outdated indexes in collection for fields  which should be stored by different new path   Mongoose adds index  when you specify field as unique

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for future developers  i recommend  delete the index in INDEX TAB using compass    this NOT DELETE ANY document in your collection Manage Indexes

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I had the same problem in my project while I social media signup  when the user joins using email first-time work without any issue  when another user signup using email there is an issue due to a null value assigned to the social media id  the reason is only one user should be allowed to insert a null value according to unique true constrain  Error Schema  facebookId        type  String      index true       Solution Schema   Drop the existing index created against facebookId   2 when we use sparse  true property it allows us to store multiple null values   facebookId        type  String      index true      unique true      sparse true

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I faced similar issues   I Just clear the Indexes of particular fields then its works for me   https   docs mongodb com v3 2 reference method db collection dropIndexes

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Please clear the collection or Delete the entire collection from MongoDB database and try again later

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I had a similar problem and I realized that by default mongo only supports one schema per collection  Either store your new schema in a different collection or delete the existing documents with the incompatible schema within the your current collection  Or find a way to have more than one schema per collection

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Here s how I solved same issue in September 2020  There is a super-fast and easy way from the mongodb atlas  cloud and desktop   Probably it was not that easy before  That is why I feel like I should write this answer in 2020  First of all  I read above some suggestions of changing the field  quot unique quot  on the mongoose schema  If you came up with this error I assume you already changed your schema  but despite of that you got a 500 as your response  and notice this  specifying duplicated KEY   If the problem was caused by schema configuration and assuming you have configurated a decent middleware to log mongo errors the response would be a 400  Why is that  In my case was simple  that field on the schema it used to accept only unique values but I just changed it to accept repeated values  Mongodb on the past created an index for that field  and so even after setting  quot unique quot  property as  quot false quot  on schema  mongodb was still using that index  Solution  Dropping that index  You can do it in 2 seconds from Mongo Atlas  Go to your collection  By default you are on  quot Find quot  tab  Just select the next one on the right   quot Indexes quot   You will see how there is still an index given to the same field is causing you trouble  Just click the button  quot Drop Index quot   I believe this is a better option than just dropping your entire collection  Basically because this is why it works after dropping the entire collection  Because mongo is not going to set an index if your first entry is using your new schema with  quot unique  false quot

User · Answer

I got this same issue when I had the following configuration in my config models js  module exports models       connection   mongodb     migrate   alter      Changing migrate from  alter  to  safe  fixed it for me   module exports models       connection   mongodb     migrate   safe

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In this situation  log in to Mongo find the index that you are not using anymore  in OP s case  email    Then select Drop Index

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Change the collection name if it already exists in the database  it will show an error  And if you given any property as unique the same error will occur

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Well basically this error is saying  that you had a unique index on a particular field for example   email address   so mongodb expects unique email address value for each document in the collection   So let s say  earlier in your schema the unique index was not defined  and then you signed up 2 users with the same email address or with no email address  null value    Later  you saw that there was a mistake  so you try to correct it by adding a unique index to the schema  But your collection already has duplicates  so the error message says that you can t insert a duplicate value again   You essentially have three options    Drop the collection   db users drop    Find the document which has that value and delete it  Let s say the value was null  you can delete it using   db users remove   email address  null     Drop the Unique index   db users dropIndex indexName    I Hope this helped

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Check indexes of that collection in MongoDB compass and remove those indexes which are not related to it or for try remove all indexes Not from code but in db

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If you are still in your development environment  I would drop the entire db and start over with your new schema    From the command line    mongo use dbName  db dropDatabase    exit

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same issue after removing properties from a schema after first building some indexes on saving  removing property from schema leads to an null value for a non existing property  that still had an index  dropping index or starting with a new collection from scratch helps here   note  the error message will lead you in that case  it has a path  that does not exist anymore  im my case the old path was     uuid 1  this is an index    but the new one is      priv uuid 1

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I have also faced this issue and I solved it  This error shows that email is already present here  So you just need to remove this line from your Model for email attribute   unique  true   This might be possible that even if it won t work  So just need to delete the collection from your MongoDB and restart your server

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This is my relavant experience   In  User  schema  I set  name  as unique key and then ran some execution  which I think had set up the database structure   Then I changed the unique key as  username   and no longer passed  name  value when I saved data to database  So the mongodb may automatically set the  name  value of new record as null which is duplicate key  I tried the set  name  key as not unique key   name   unique  false  type  String   in  User  schema in order to override original setting  However  it did not work   At last  I made my own solution   Just set a random key value that will not likely be duplicate to  name  key when you save your data record  Simply Math method      Math random     Math random    makes a random string

User · Answer

I had the same issue  Tried debugging different ways couldn t figure out  I tried dropping the collection and it worked fine after that  Although this is not a good solution if your collection has many documents  But if you are in the early state of development try dropping the collection   db users drop

User · Answer

I had the same issue when i tried to modify the schema defined using mangoose  I think the issue is due to the reason that there are some underlying process done when creating a collection like describing the indices which are hidden from the user at least in my case  So the best solution i found was to drop the entire collection and start again

User · Answer

I was facing similar issue  I went about clearing idexes and restarting server and probably almost everything mentioned here according to my understanding and still there was error  turns out the jsonwebtoken secret key that i was passing was undefined  if you are using jsonwebtoken  do check it once

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It s not a big issue but beginner level developers as like me  we things what kind of error is this and finally we weast huge time for solve it  Actually if you delete the db and create the db once again and after try to create the collection then it s will be work properly    mongo use dbName  db dropDatabase    exit

User · Answer

I had same Issue  Problem was that I have removed one field from model  When I dropped db it fixes

[node.js] E11000 duplicate key error index in mongodb mongoose

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