Hi folks!
After install search plugin and run ./nodebb upgrade, i give this error:

./nodebb upgrade

Updating NodeBB...

1. Updating package.json file with defaults...  OK

2. Bringing base dependencies up to date...  started
npm WARN [email protected] requires a peer of nodebb-plugin-emoji@^2.0.0 but none is installed. You must install peer dependencies yourself.
npm WARN [email protected] requires a peer of textcomplete@^0.14.2 but none is installed. You must install peer dependencies yourself.

audited 3651 packages in 9.472s
found 9 vulnerabilities (2 low, 4 moderate, 3 high)
  run `npm audit fix` to fix them, or `npm audit` for details

3. Checking installed plugins for updates...(node:2159) DeprecationWarning: current Server Discovery and Monitoring engine is deprecated, and will be removed in a future version. To use the new Server Discover and Monitoring engine, pass option { useUnifiedTopology: true } to MongoClient.connect.
Warning: no saslprep library specified. Passwords will not be sanitized
  OK
4. Updating NodeBB data store schema...Warning: no saslprep library specified. Passwords will not be sanitized

Parsing upgrade scripts...
OK | 1 script(s) found, 78 skipped
Warning: no saslprep library specified. Passwords will not be sanitized
  → [2018/11/26] Changing dbsearch mongodb search schema to use _id...
2019-08-20T21:21:15.085Z [4567/2159] - error: ns not found {"ok":0,"errmsg":"ns not found","code":26,"codeName":"NamespaceNotFound","name":"MongoError"}
2019-08-20T21:21:15.087Z [4567/2159] - error: ns not found {"ok":0,"errmsg":"ns not found","code":26,"codeName":"NamespaceNotFound","name":"MongoError"}

And stuck on this .
Any help?

Ubuntu Server 18.04.3
Mongodb 4.0.12
Node v10.16.3
Npm 6.11.0