MongoDB 3.6 crashed due to invariant() failure MongoDB crashed twice in 6 hours today due to invariant() failure. We have been using MongoDB 3.6.3 for more than a year now, but this is the first time that we saw this issue. The extract from the log files is given below for reference -

Log from 1st failure:


  2019-02-27T08:44:51.411+0530 E STORAGE  [conn3385299] WiredTiger error
  (12) [1551237291:411637][2344:2000827264],
  file:collection-17055--5635302636308412295.wt, WT_CURSOR.search:
  C:/MREYE/MongoDB/data\collection-17055--5635302636308412295.wt:
  handle-read: ReadFile: failed to read 4096 bytes at offset 720363520:
  Not enough storage is available to process this command.
  
  : Not enough space 2019-02-27T08:44:51.412+0530 F -
  [conn3385299] Invariant failure: seekRet resulted in status
  UnknownError: 12: Not enough space at
  src\mongo\db\storage\wiredtiger\wiredtiger_record_store.cpp 1734
  
  
    2019-02-27T08:44:51.412+0530 F -        [conn3385299]
  
  
  ***aborting after invariant() failure


Log from 2nd failure:


  2019-02-27T13:44:11.594+0530 E STORAGE  [conn20] WiredTiger error (12)
  [1551255251:594637][54524:2000827264],
  file:collection-17071--5635302636308412295.wt, WT_CURSOR.search:
  memory allocation of 28696 bytes failed: Not enough space
  
  2019-02-27T13:44:11.594+0530 F -        [conn20] Invariant failure:
  seekRet resulted in status UnknownError: 12: Not enough space at
  src\mongo\db\storage\wiredtiger\wiredtiger_record_store.cpp 1734
  
  2019-02-27T13:44:11.595+0530 F -        [conn20] 
  
  ***aborting after invariant() failure


Note:

The MongoDB is on C drive and there is sufficient space left (276 GB) on that drive. The MongoDB data folder size itself is only 65 GB. Any idea what might have caused this issue?
It looks like the problem is not with your physical memory. 

What is the RAM size you are using? Are there any other applications that are consuming more RAM memory?

Refer the below thread for more details

Invariant failure: seekRet resulted in status