v2.5.3 and later - Unhandled exception. System.FormatException: One of the identified items was in an invalid format.

[tsjk]

info: Configuration:  Data Directory: /datadir
info: Configuration:  Configuration File: /datadir/Main/settings.config
info: Configuration:  Network: Mainnet
info: Configuration:  Supported chains: BTC,LBTC
Unhandled exception. System.FormatException: One of the identified items was in an invalid format.
   at NBXplorer.Configuration.ConfigurationExtensions.GetOrDefault[T](IConfiguration configuration, String key, T defaultValue) in /source/NBXplorer/Configuration/ConfigurationExtensions.cs:line 23
   at NBXplorer.Configuration.ExplorerConfiguration.<>c__DisplayClass28_0.<LoadArgs>b__2(String o) in /source/NBXplorer/Configuration/ExplorerConfiguration.cs:line 206
   at System.Linq.Enumerable.WhereArrayIterator`1.MoveNext()
   at System.String.Join(String separator, IEnumerable`1 values)
   at NBXplorer.Configuration.ExplorerConfiguration.LoadArgs(IConfiguration config) in /source/NBXplorer/Configuration/ExplorerConfiguration.cs:line 204
   at NBXplorer.Program.Main(String[] args) in /source/NBXplorer/Program.cs:line 29

My config file has no uncommented lines.

####Common Commands####
####If Bitcoin Core is running with default settings, you should not need to modify this file####
####All those options can be passed by through command like arguments (ie `-port=19382`)####

## This is the RPC Connection to your node
#btc.rpc.url=http://127.0.0.1:8332/
#By user name and password
#btc.rpc.user=bitcoinuser
#btc.rpc.password=bitcoinpassword
#By cookie file
#btc.rpc.cookiefile=yourbitcoinfolder/.cookie
#By raw authentication string
#btc.rpc.auth=walletuser:password

## This is the connection to your node through P2P
#btc.node.endpoint=127.0.0.1:BTC

## minutxovalue defines the minimum value allowed for a utxo to be tracked
#btc.minutxovalue=1

## startheight defines from which block you will start scanning, if -1 is set, it will use current blockchain height
#btc.startheight=-1
## rescan forces a rescan from startheight
#btc.rescan=0
## rescaniftimebefore only lets rescan occur if current unix timestamp (seconds) is less than the given value
## requires btc.rescan to be true
#btc.rescaniftimebefore=1635210000


## If more than 0, the size of the cache for the database, in MB. Else, no limit on the size of the cache. (default: 50)
#dbcache=50
## Disable cookie, local ip authorization (unsecured)
#noauth=0
## Add a server alias to be returned in status response
#instancename=nbxplorer
## Expose the node RPC through the REST API
#exposerpc=0
## What crypto currencies is supported
#chains=btc
## Activate or disable verbose logs
#verbose=0


####Server Commands####
#port=24444
#bind=127.0.0.1
#mainnet=1


####Azure Service Bus####
## Azure Service Bus configuration - set connection string to use Service Bus. Set Queue and / or Topic names to publish message to queues / topics
#asbcnstr=Endpoint=sb://<yourdomain>.servicebus.windows.net/;SharedAccessKeyName=<your key name here>;SharedAccessKey=<your key here>
#asbblockq=<new block queue name>
#asbtranq=<new transaction queue name>
#asbblockt=<new block topic name>
#asbtrant=<new transaction topic name>

And the environments is:

    -e NBXPLORER_DBCACHE="256"
    -e NBXPLORER_NETWORK="mainnet" -e NBXPLORER_BIND="0.0.0.0:32838" -e NBXPLORER_NOAUTH="0"
    -e NBXPLORER_INSTANCENAME="nbxplorer" -e NBXPLORER_EXPOSERPC="1"
    -e NBXPLORER_POSTGRES="Host=db;Port=5432;User ID=<snip>;Password=<snip>;Database=nbxplorer;"
    -e NBXPLORER_CHAINS="btc,lbtc"
    -e NBXPLORER_BTCNODEENDPOINT="host.containers.internal:8333" -e NBXPLORER_BTCRPCURL="http://host.containers.internal:8332/"
    -e NBXPLORER_BTCHASTXINDEX="true"
    -e NBXPLORER_BTCRPCUSER="bitcoind_rpc" -e NBXPLORER_BTCRPCPASSWORD="<snip>"
    -e NBXPLORER_LBTCNODEENDPOINT="host.containers.internal:7042" -e NBXPLORER_LBTCRPCURL="http://host.containers.internal:7041/"
    -e NBXPLORER_LBTCHASTXINDEX="true"
    -e NBXPLORER_LBTCRPCUSER="elementsd_rpc" -e NBXPLORER_LBTCRPCPASSWORD="<snip>" \

[NicolasDorier]

seems to come from https://github.com/dgarage/NBXplorer/blob/v2.5.3/NBXplorer/Configuration/ExplorerConfiguration.cs#L204

It is caused by NBXPLORER_DBCACHE="256". Remove this, this isn't used anymore.