Elasticsearch index closed, won't recover, won't open

I'm trying to recover a closed index but any attempt to do so is so far unsuccessful.

GET /_cat/indices/ shows:

green open  .fess_config.web_config            m7yOnyvERje6baMyvi5IHA  2 0     1   0    10kb    10kb
      close .suggest_analyzer                  fjKXYnKHSQOeVsqf_ETTVA                               
green open  .fess_user.group                   jyu086_5QUKmx9N64EHsRQ  5 0     0   0   1.2kb   1.2kb

GET /_cluster/health?level=indices&pretty doesn't contain fjKXYnKHSQOeVsqf_ETTVA in its output at all.

There is also no mention whatsoever¹ of fjKXYnKHSQOeVsqf_ETTVA in the startup log.

GET /.suggest_analyzer/fjKXYnKHSQOeVsqf_ETTVA/_recovery?human and
GET /.suggest_analyzer/fjKXYnKHSQOeVsqf_ETTVA/_open results in:

{
    "error": {
        "root_cause": [{
                "type": "index_closed_exception",
                "reason": "closed",
                "index_uuid": "fjKXYnKHSQOeVsqf_ETTVA",
                "index": ".suggest_analyzer"
            }
        ],
        "type": "index_closed_exception",
        "reason": "closed",
        "index_uuid": "fjKXYnKHSQOeVsqf_ETTVA",
        "index": ".suggest_analyzer"
    },
    "status": 400
}

GET /_recovery?human returns that everything is OK, yet there is again no mention of fjKXYnKHSQOeVsqf_ETTVA in the response.

There are also no *recovery files on the filesystem:

[root@mmm indices]# ls -lR fjKXYnKHSQOeVsqf_ETTVA
fjKXYnKHSQOeVsqf_ETTVA:
drwxr-xr-x 5 elasticsearch elasticsearch 4096 Mar 19 11:33 0
drwxr-xr-x 5 elasticsearch elasticsearch 4096 Mar 19 11:33 1
drwxr-xr-x 5 elasticsearch elasticsearch 4096 Mar 19 11:33 2
drwxr-xr-x 5 elasticsearch elasticsearch 4096 Mar 19 11:33 3
drwxr-xr-x 5 elasticsearch elasticsearch 4096 Mar 19 11:33 4
drwxr-xr-x 2 elasticsearch elasticsearch 4096 Mar 19 11:33 _state

fjKXYnKHSQOeVsqf_ETTVA/0:
drwxr-xr-x 2 elasticsearch elasticsearch 4096 Mar 19 11:33 index
drwxr-xr-x 2 elasticsearch elasticsearch 4096 Mar 19 11:33 _state
drwxr-xr-x 2 elasticsearch elasticsearch 4096 Mar 19 11:33 translog

fjKXYnKHSQOeVsqf_ETTVA/0/index:
-rw-r--r-- 1 elasticsearch elasticsearch 230 Mar 16 11:03 segments_1
-rw-r--r-- 1 elasticsearch elasticsearch   0 Mar 16 11:03 write.lock

fjKXYnKHSQOeVsqf_ETTVA/0/_state:
-rw-r--r-- 1 elasticsearch elasticsearch 125 Mar 16 11:03 state-0.st

fjKXYnKHSQOeVsqf_ETTVA/0/translog:
-rw-r--r-- 1 elasticsearch elasticsearch 43 Mar 16 11:03 translog-1.tlog
-rw-r--r-- 1 elasticsearch elasticsearch 80 Mar 16 11:03 translog.ckp

fjKXYnKHSQOeVsqf_ETTVA/1:
drwxr-xr-x 2 elasticsearch elasticsearch 4096 Mar 19 11:33 index
drwxr-xr-x 2 elasticsearch elasticsearch 4096 Mar 19 11:33 _state
drwxr-xr-x 2 elasticsearch elasticsearch 4096 Mar 19 11:33 translog

fjKXYnKHSQOeVsqf_ETTVA/1/index:
-rw-r--r-- 1 elasticsearch elasticsearch 230 Mar 16 11:03 segments_1
-rw-r--r-- 1 elasticsearch elasticsearch   0 Mar 16 11:03 write.lock

fjKXYnKHSQOeVsqf_ETTVA/1/_state:
-rw-r--r-- 1 elasticsearch elasticsearch 125 Mar 16 11:03 state-0.st

fjKXYnKHSQOeVsqf_ETTVA/1/translog:
-rw-r--r-- 1 elasticsearch elasticsearch 43 Mar 16 11:03 translog-1.tlog
-rw-r--r-- 1 elasticsearch elasticsearch 80 Mar 16 11:03 translog.ckp

fjKXYnKHSQOeVsqf_ETTVA/2:
drwxr-xr-x 2 elasticsearch elasticsearch 4096 Mar 19 11:33 index
drwxr-xr-x 2 elasticsearch elasticsearch 4096 Mar 19 11:33 _state
drwxr-xr-x 2 elasticsearch elasticsearch 4096 Mar 19 11:33 translog

fjKXYnKHSQOeVsqf_ETTVA/2/index:
-rw-r--r-- 1 elasticsearch elasticsearch 230 Mar 16 11:03 segments_1
-rw-r--r-- 1 elasticsearch elasticsearch   0 Mar 16 11:03 write.lock

fjKXYnKHSQOeVsqf_ETTVA/2/_state:
-rw-r--r-- 1 elasticsearch elasticsearch 125 Mar 16 11:03 state-0.st

fjKXYnKHSQOeVsqf_ETTVA/2/translog:
-rw-r--r-- 1 elasticsearch elasticsearch 43 Mar 16 11:03 translog-1.tlog
-rw-r--r-- 1 elasticsearch elasticsearch 80 Mar 16 11:03 translog.ckp

fjKXYnKHSQOeVsqf_ETTVA/3:
drwxr-xr-x 2 elasticsearch elasticsearch 4096 Mar 19 11:33 index
drwxr-xr-x 2 elasticsearch elasticsearch 4096 Mar 19 11:33 _state
drwxr-xr-x 2 elasticsearch elasticsearch 4096 Mar 19 11:33 translog

fjKXYnKHSQOeVsqf_ETTVA/3/index:
-rw-r--r-- 1 elasticsearch elasticsearch 230 Mar 16 11:03 segments_1
-rw-r--r-- 1 elasticsearch elasticsearch   0 Mar 16 11:03 write.lock

fjKXYnKHSQOeVsqf_ETTVA/3/_state:
-rw-r--r-- 1 elasticsearch elasticsearch 125 Mar 16 11:03 state-0.st

fjKXYnKHSQOeVsqf_ETTVA/3/translog:
-rw-r--r-- 1 elasticsearch elasticsearch 43 Mar 16 11:03 translog-1.tlog
-rw-r--r-- 1 elasticsearch elasticsearch 80 Mar 16 11:03 translog.ckp

fjKXYnKHSQOeVsqf_ETTVA/4:
drwxr-xr-x 2 elasticsearch elasticsearch 4096 Mar 19 11:33 index
drwxr-xr-x 2 elasticsearch elasticsearch 4096 Mar 19 11:33 _state
drwxr-xr-x 2 elasticsearch elasticsearch 4096 Mar 19 11:33 translog

fjKXYnKHSQOeVsqf_ETTVA/4/index:
-rw-r--r-- 1 elasticsearch elasticsearch 230 Mar 16 11:03 segments_1
-rw-r--r-- 1 elasticsearch elasticsearch   0 Mar 16 11:03 write.lock

fjKXYnKHSQOeVsqf_ETTVA/4/_state:
-rw-r--r-- 1 elasticsearch elasticsearch 125 Mar 16 11:03 state-0.st

fjKXYnKHSQOeVsqf_ETTVA/4/translog:
-rw-r--r-- 1 elasticsearch elasticsearch 43 Mar 16 11:03 translog-1.tlog
-rw-r--r-- 1 elasticsearch elasticsearch 80 Mar 16 11:03 translog.ckp

fjKXYnKHSQOeVsqf_ETTVA/_state:
-rw-r--r-- 1 elasticsearch elasticsearch 71958 Mar 19 11:33 state-7.st

[root@mmm indices]#

So how to force ES to open this index?

¹ The recovery of the index failed twice due to a missing file, but that issue has already been resolved, and now ES won't even attempt to recover/open it.

Solution

Solved with:

POST /_all/_open

With an empty JSON body {}

$ curl -XPOST "http://localhost:9200/_all/_open" -H "Content-Type: application/json" -d "{}"
{
    "acknowledged": true,
    "shards_acknowledged": true
}

GET /_cat/indices/

green open  .fess_config.web_config            m7yOnyvERje6baMyvi5IHA  2 0     1   0    10kb    10kb
green open  .suggest_analyzer                  fjKXYnKHSQOeVsqf_ETTVA  5 0     0     0   1.2kb   1.2kb
green open  .fess_user.group                   jyu086_5QUKmx9N64EHsRQ  5 0     0   0   1.2kb   1.2kb