You can fix the issue by increasing the value of index.mapping.total_fields.limit (default 1000)
index.mapping.total_fields.limit
The maximum number of fields in an index. Field and object mappings, as well as field aliases count towards this limit. The default value is 1000.
To increase total fields limit to 2000, try this
PUT test_index/_settings
{
"index.mapping.total_fields.limit": 2000
}
The reason to limit the number of fields is :
Defining too many fields in an index is a condition that can lead to a mapping explosion, which can cause out of memory errors and difficult situations to recover from. This is quite common with dynamic mappings. Every time a document contains new fields, those will end up in the index’s mappings
Related Resources :
1. Get the number of fields on an index
2. Settings to prevent mappings explosion