# Frequently Encountered Issues These are fixes or information for common issues encountered by Go Driver users. If none of these are helpful, [create a GODRIVER Jira ticket](https://jira.mongodb.org/secure/CreateIssue!default.jspa) and we'll try to troubleshoot your issue! ## `WriteXXX` can only write while positioned on a Element or Value but is positioned on a TopLevel The [`bson.Marshal`](https://pkg.go.dev/go.mongodb.org/mongo-driver/bson#Marshal) function requires a parameter that can be decoded into a BSON Document, i.e. a [`primitive.D`](https://github.com/mongodb/mongo-go-driver/blob/master/bson/bson.go#L31). Therefore the error message > `WriteXXX` can only write while positioned on a Element or Value but is positioned on a TopLevel occurs when the input to `bson.Marshal` is something *other* than a BSON Document. Examples of this occurrence include - `WriteString`: the input into `bson.Marshal` is a string - `WriteNull`: the input into `bson.Marshal` is null - `WriteInt32`: the input into `bson.Marshal` is an integer Many CRUD operations in the Go Driver use `bson.Marshal` under the hood, so it's possible to encounter this particular error without directly attempting to encode data. For example, when using a sort on [`FindOneAndUpdate`](https://pkg.go.dev/go.mongodb.org/mongo-driver/mongo#Collection.FindOneAndUpdate) this error can occur when not properly initializing the `sort` variable: ```go var sort bson.D // this is nil and will result in a WriteNull error opts := options.FindOneAndUpdate().SetSort(sort) update := bson.D{{"$inc", bson.D{{"x", 1}}}} sr := coll.FindOneAndUpdate(ctx, bson.D{}, update) if err := sr.Err(); err != nil { log.Fatalf("error getting single result: %v", err) } ``` The above example is resolved by initializing the `sort` variable: ```go sort := bson.D{} ``` ## Convert BSON Document to JSON There are a variety of marshalers that can be used to encode a BSON document as JSON, including [MarshalExtJSON](https://pkg.go.dev/github.com/mongodb/mongo-go-driver/bson#MarshalExtJSON): ```go doc := bson.D{{"x", 1}} jsonBytes, err := bson.MarshalExtJSON(doc, true, false) if err != nil { log.Fatalf("error encoding json: %v", err) } m := make(map[string]interface{}) if err := json.Unmarshal(jsonBytes, &m); err != nil { log.Fatalf("error decoding json: %v", err) } fmt.Printf("json: %v\n", m) ``` ## Authentication Failed When connecting to a MongoDB deployment with password authentication enabled, if your authentication information or configuration are incorrect, you may encounter an error message like: > connection() error occurred during connection handshake: auth error: sasl conversation error: unable to authenticate using mechanism "SCRAM-SHA-256": (AuthenticationFailed) Authentication failed. That error can be caused by a number of issues. The error message intentionally omits the exact authentication failure reason (see the [OWASP Authentication and Error Messages guidelines](https://cheatsheetseries.owasp.org/cheatsheets/Authentication_Cheat_Sheet.html#authentication-and-error-messages) for an explanation). Possible causes of the error include: - Incorrect password. - Incorrect username. - Incorrect authentication database (i.e. [authSource](https://www.mongodb.com/docs/manual/reference/connection-string/#mongodb-urioption-urioption.authSource)). If you encounter an `AuthenticationFailed` error like the one above, check that the username and password in your [connection string](https://www.mongodb.com/docs/manual/reference/connection-string/) or [SetAuth](https://pkg.go.dev/go.mongodb.org/mongo-driver/mongo/options#ClientOptions.SetAuth) call are correct. In most cases, [authSource](https://www.mongodb.com/docs/manual/reference/connection-string/#mongodb-urioption-urioption.authSource) does not need to be specified unless you are using a non-default authentication database (the default is "admin").