diff --git a/python/obitools3/commands/ngsfilter.pyx b/python/obitools3/commands/ngsfilter.pyx
index 53d7827..89ae5ba 100644
--- a/python/obitools3/commands/ngsfilter.pyx
+++ b/python/obitools3/commands/ngsfilter.pyx
@@ -172,6 +172,13 @@ cdef read_info_view(info_view, max_errors=2, verbose=False, not_aligned=False):
     primer_list = []
     i=0
     for p in info_view:
+        
+        # Check primer length: should not be longer than 32, the max allowed by the apat lib
+        if len(p[b'forward_primer']) > 32:
+            raise RollbackException("Error: primers can not be longer than 32bp, rollbacking views")
+        if len(p[b'reverse_primer']) > 32:
+            raise RollbackException("Error: primers can not be longer than 32bp, rollbacking views")
+        
         forward=Primer(p[b'forward_primer'],
                        len(p[b'forward_tag']) if (b'forward_tag' in p and p[b'forward_tag']!=None) else None,
                        True,
@@ -594,7 +601,13 @@ def run(config):
     pb = ProgressBar(entries_len, config, seconde=5)
 
     # Check and store primers and tags
-    infos, primer_list = read_info_view(info_view, max_errors=config['ngsfilter']['error'], verbose=False, not_aligned=not_aligned)   # TODO obi verbose option
+    try:
+        infos, primer_list = read_info_view(info_view, max_errors=config['ngsfilter']['error'], verbose=False, not_aligned=not_aligned)   # TODO obi verbose option
+    except RollbackException, e:
+        if unidentified is not None:
+            raise RollbackException("obi ngsfilter error, rollbacking views: "+str(e), o_view, unidentified)
+        else:
+            raise RollbackException("obi ngsfilter error, rollbacking view: "+str(e), o_view)
     
     aligner = Primer_search(primer_list, config['ngsfilter']['error'])
     
@@ -652,11 +665,11 @@ def run(config):
     #print("\n\nOutput view:\n````````````", file=sys.stderr)
     #print(repr(o_view), file=sys.stderr)
 
-    input[0].close()
-    output[0].close()
-    info_input[0].close()
+    input[0].close(force=True)
+    output[0].close(force=True)
+    info_input[0].close(force=True)
     if unidentified is not None:
-        unidentified_input[0].close()
+        unidentified_input[0].close(force=True)
     aligner.free()
 
     logger("info", "Done.")