Getting multi-part identifier "column name" could not be bound error in SQL Server of newer version - sql

Question

I have this code for my stored procedure:
create or alter procedure udpReservationFilter
#FName nvarchar(160),
#LName nvarchar(160),
#Category nvarchar(160),
#Number int,
#TotalCount int OUT,
#ColumnName nvarchar(100) = 'M.Id',
#SortDesc bit = 0,
#Page int = 1,
#PageSize int = 2
as
begin
declare #sqlWhere nvarchar(max) = ''
declare #whereParams nvarchar(1000) = N' #FName nvarchar(160),
#LName nvarchar(160),
#Category nvarchar(160),
#Number int, #OffsetRows int, #PageSize int'
declare #countParams nvarchar(1000) = N' #FName nvarchar(160),
#LName nvarchar(160),
#Category nvarchar(160),
#Number int,
#TotalCount int OUT'
if len(trim(#FName)) > 0
set #sqlWhere += ' AND c.FName like ''%'' + #FName + ''%'' '
if len(trim(#LName)) > 0
set #sqlWhere += ' AND c.LName like #LName '
if len(trim(#Category))> 0
set #sqlWhere += ' AND r.Category like #Category '
if (#Number > 0)
set #sqlWhere += ' AND r.Number = #Number '
---------------- counting total results -------------------
declare #sqlCount nvarchar(1000) = N' select #TotalCount = count(*) from Reservations M '
if len(#sqlWhere) > 0
set #sqlCount = #sqlCount + ' where ' + (SUBSTRING(#sqlWhere, 5 , 60))
exec sp_executesql #sqlCount,
#countParams,
#FName = #FName,
#LName = #LName,
#Category = #Category,
#Number = #Number,
#TotalCount = #TotalCount OUT
declare #sql nvarchar(max) = N' select M.*, c.*, r.Category, r.Number, r.Price, r.Status
from Reservations M, Client c, Rooms r
where M.ClientId=c.ID and M.RoomId=r.Id'
+ #sqlWhere
+ ' order by ' + #ColumnName
+ ' offset #OffsetRows rows fetch next #PageSize rows only'
--M.*, c.*, r.Number, r.category, r.Price, r.status
declare #Offset int = (#Page-1)*#PageSize
if #Offset < 0
set #Offset = 0
exec sp_executesql #sql,
#whereParams,
#FName = #FName,
#LName =#LName,
#Category = #Category,
#Number = #Number,
#OffsetRows = #Offset,
#PageSize = #PageSize
end
I'm getting this error:
The multi-part identifier "column_name" could not be bound.
when executing the query.
declare #cnt int
exec udpReservationFilter
#FName = null,
#LName = null,
#Category = null,
#Number = null,
#TotalCount = #cnt OUT,
#PageSize = 3
When I provide parameters it is above error and gives the matched result this error stops my asp.net core app and if there is no parameters provided its compiling without error
Here is more detailed error :
Msg 4104, Level 16, State 1, Line 5
The multi-part identifier "c.FName" could not be bound.
(1 row affected)