Reindexing Old index

I want to reindex old index but the problem my alias is writing to current index

health status index                            uuid                   pri rep docs.count docs.deleted store.size pri.store.size
green  open   log-wlb-sysmon-2021.06.09-000007 9CmsyVUGT26UwxID3LT8Xw   1   1   82308203        53179      100gb           50gb
green  open   log-wlb-sysmon-2021.05.31-000006 nL70VTUmQ7iuPsJusGHBsw   1   1   85460152        89372     99.9gb           50gb
green  open   log-wlb-sysmon-2021.06.25-000009 HXwRnl8QRq6F_BCmztlBHw   1   1   78000899        38081      100gb           50gb
green  open   log-wlb-sysmon-2021.07.10-000010 cL1mz5t4RWyNXaoCFmU-cw   1   1   65473320            0     83.1gb         41.5gb
green  open   log-wlb-sysmon-2021.06.17-000008 VMIdvZhhQ7eDrtBrrk2t0w   1   1   81276018        46164      100gb         49.9gb
green  open   log-wlb-sysmon-2021.07.11-000011 rhKip49IRLeK2Ifjzodd-g   1   1     402028        38730    543.7mb        274.6mb

i am facing maping conflict problem in log-wlb-sysmon-2021.06.17-000008 how can i reindex my old index
i ran the following commands:
1.

{
"aliases": {
   "log-wlb-sysmon": {
      "is_write_index": false  
   }
 }
}
POST _reindex?max_docs=	81276018&wait_for_completion=false
{
  "conflicts": "proceed"
  , "source": {
    "index": "log-wlb-sysmon-2021.06.17-000008"
    },
   "dest": {
    "index": "log-wlb-sysmon-2021.07.11-000008"
  }
}

after a minute i phase java.lang.IllegalArgumentException: index.lifecycle.rollover_alias [log-wlb-sysmon] does not point to index [log-wlb-sysmon-2021.07.11-000008]
log-wlb-sysmon(alias) is writing log-wlb-sysmon-2021.07.10-000010
I also tried to change alias name nothing happened

PUT %3Clog-wlb-sysmon-%7Bnow%2Fd%7D-000008%3E 
{
"aliases": {
   "<log-wlbsysmon_{now/M}>": {
      "is_write_index": true     
   }
 }
}

How can i reindex my old index data and also my current alias is also writing to current index

@Aniket_Pant

Based on index names looks like your trying to reindex older data into a current index. I'd suggest just adding "-reindex" to the destination index.

POST _reindex?max_docs=	81276018&wait_for_completion=false
{
  "conflicts": "proceed"
  , "source": {
    "index": "log-wlb-sysmon-2021.06.17-000008"
    },
   "dest": {
    "index": "log-wlb-sysmon-2021.06.17-000008-reindex"
  }
}

Also, after you create new destination remove any alias from the destination index.

Hope this helps.

Cheers,
Rich

illegal_argument_exception: index [log-wlb-sysmon-2021.07.18-000019] is not the write index for alias [log-wlb-sysmon]
I am getting this error
i made an index , i am using ilm so i need to create this timeseries indices
After that

PUT %3Clog-wlb-sysmon-reindex-%7Bnow%2Fd%7D-000020%3E  
{
"aliases": {
   "log-wlb-sysmon": {
      "is_write_index": false     
   }
 }
}
POST _reindex?max_docs=1623237&wait_for_completion=false
{
  "conflicts": "proceed"
  , "source": {
    "index": "log-wlb-sysmon-2021.07.17-000018"
    
  }
  , "dest": {
    "index": "log-wlb-sysmon-reindex-2021.07.18-000021"
  }
}

basically i want live data also and past data also like today data is streaming to today index and past data is also streaming to the index we've created