SSIS Package SQL Task failing

I have SSIS package and it runs every hour. This package import data from csv into database table. From march 2017 this package has been failing. What i see there is a SQL task step which is failing but before it was succeeded. Here is the below code:-- I put the four *** sign where it is failing.


declare @toparse nvarchar(max)
declare @strlength int
declare @separator_location int
declare @instance nchar(10)

declare @instance_url nvarchar(max)

declare @hostname nvarchar(50)
declare @strIn nvarchar(2000)
declare @separator nchar(2) = ' '
declare @inner_separator nchar(1) = '|'

DECLARE @item nvarchar(1000)  -- assume maximun item length 1000 char
DECLARE @len int, @sepPos1 int,  @sepPos2 int

-- truncate table staging_oracle_version
--declare @truncate varchar(200)
--set @truncate = 'truncate table staging_oracle_version'
--exec (@truncate)

-- get oracle instances to load
declare  oracleinstance_csr cursor for
select certname
      , value
from puppetdb_certname_facts
where fact like 'oracle_instance_url'
   and value IS NOT NULL
   and value !=''
  and value != '""'

open oracleinstance_csr

fetch next from oracleinstance_csr into @hostname, @strIn

--select @hostname, @strIn

while @@FETCH_STATUS = 0
begin

  SET @strIn = REPLACE(@strIn, char(10), @separator)  -- Replace all the LF (char(10)) from the string and replace with defined separator [ the code for CR is char(13)]
  Set @sepPos1 = 1
  set @sepPos2 = charindex(@separator, @strIn)

  SET @strin = @strIn + @separator

  IF @sepPos2 = 0  -- nothing to parse here
  BEGIN
     SET @item = @strIn
     SET @toparse =  ( RTRIM(LTRIM(@item)))
     
       select @strlength = LEN(@toparse)
       select @separator_location = charindex(@inner_separator, @toparse)

      
****       select @instance = LEFT(@toparse,(@separator_location-1))
       select @instance_url = RIGHT(@toparse, (@strlength-@separator_location))

        update oracleinstances
        set instance_url  = @instance_url
        where instanceName = @instance
          and hostname = @hostname
       -- select @instance, @hostname, @version
      
  END
ELSE
  BEGIN
    WHILE @sepPos2 > 0
    BEGIN
        -- get parse through the values
      SET @item = substring(@strIn, @sepPos1,@sepPos2-1)
      SET @toparse =  ( RTRIM(LTRIM(@item)))
     
        select @strlength = LEN(@toparse)
        select @separator_location = charindex(@inner_separator, @toparse)

        select @instance = LEFT(@toparse,(@separator_location-1))
        select @instance_url = RIGHT(@toparse, (@strlength-@separator_location))

        
        update oracleinstances
        set instance_url = @instance_url
        where instanceName = @instance
          and hostname = @hostname

      SET @sepPos1 = @sepPos1 + @sepPos2
      set @sepPos2 = charindex(@separator, substring(@strIn, @sepPos1,100))
    END
 

  END

  fetch next from oracleinstance_csr into @hostname, @strIn
           
END

close oracleinstance_csr
deallocate oracleinstance_csr

Error:

Msg 537, Level 16, State 3, Line 56
Invalid length parameter passed to the LEFT or SUBSTRING function.