diff --git a/Exareme-Docker/src/exareme/exareme-tools/madis/src/functionslocal/row/errorchecking.py b/Exareme-Docker/src/exareme/exareme-tools/madis/src/functionslocal/row/errorchecking.py
index 922669a29..84e7a8aa5 100644
--- a/Exareme-Docker/src/exareme/exareme-tools/madis/src/functionslocal/row/errorchecking.py
+++ b/Exareme-Docker/src/exareme/exareme-tools/madis/src/functionslocal/row/errorchecking.py
@@ -95,6 +95,16 @@ def histograms_inputerrorchecking(xisCategorical,bins):
 histograms_inputerrorchecking.registered = True
 
 
+def pairedttest_inputerrorchecking(variableNo):
+    if variableNo%2 == 1:
+        raise functions.OperatorError("ExaremeError", "The input should be in the form of y1-y2,y3-y4,.. Therefore the number of variables should be modulo 2")            
+    else:
+        return "OK"
+
+pairedttest_inputerrorchecking.registered = True
+
+
+
 if not ('.' in __name__):
     """
     This is needed to be able to test the function, put it at the end of every
diff --git a/Exareme-Docker/src/mip-algorithms/TTEST_PAIRED/local.template.sql b/Exareme-Docker/src/mip-algorithms/TTEST_PAIRED/local.template.sql
index 174c344d7..b4b18c67e 100644
--- a/Exareme-Docker/src/mip-algorithms/TTEST_PAIRED/local.template.sql
+++ b/Exareme-Docker/src/mip-algorithms/TTEST_PAIRED/local.template.sql
@@ -12,6 +12,16 @@ var 'xnames' from
 select group_concat(xname) as  xname from
 (select distinct xname from (select strsplitv(regexpr("\-",'%{x}',"+") ,'delimiter:+') as xname) where xname!=0);
 
+
+--Check input: number of variables is modulo 2 
+select pairedttest_inputerrorchecking(no) from
+(select count(*) as no from
+(select strsplitv(xname,'dialect:csv') from
+(select group_concat(xname) as  xname from
+(select distinct xname from (select strsplitv(regexpr("\-",'%{x}',"+") ,'delimiter:+') as xname) where xname!=0))));
+
+
+
 --Read dataset and Cast values of columns using cast function.
 var 'cast_x' from select create_complex_query("","tonumber(?) as ?", "," , "" , '%{xnames}');
 drop table if exists localinputtblflat;
diff --git a/Exareme-Docker/src/mip-algorithms/tests/exareme_tests/test_parameters.py b/Exareme-Docker/src/mip-algorithms/tests/exareme_tests/test_parameters.py
index f0d969f12..fbd534d60 100644
--- a/Exareme-Docker/src/mip-algorithms/tests/exareme_tests/test_parameters.py
+++ b/Exareme-Docker/src/mip-algorithms/tests/exareme_tests/test_parameters.py
@@ -8,6 +8,27 @@
 from tests import vm_url
 
 
+
+def test_parameter_modulo2():
+
+    endpointUrl1 = vm_url + "TTEST_PAIRED"
+
+    logging.info("---------- TEST : t-test input parameters throwing error.")
+    data = [
+       {"name": "y", "value": "lefthippocampus-righthippocampus,leftententorhinalarea"},
+       {"name": "hypothesis", "value": "different"},
+       {"name": "pathology", "value": "dementia"},
+       {"name": "dataset", "value": "desd-synthdata"},
+       {"name": "filter", "value": ""},
+    ]
+    headers = {"Content-type": "application/json", "Accept": "text/plain"}
+    r = requests.post(endpointUrl1, data=json.dumps(data), headers=headers)
+    result = json.loads(r.text)
+    assert(result["result"][0]["data"]==" The input should be in the form of y1-y2,y3-y4,.. Therefore the number of variables should be modulo 2 ")
+    assert(result["result"][0]["type"]=="text/plain+user_error")
+    
+
+
 def test_valueEnumerationsParameter():
 
     endpointUrl1 = vm_url + "LINEAR_REGRESSION"