Ok try this:

# store a reference to the hash
# note the backslash!
$session->param("access", \%access);
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Now to retrieve your data:

#retrieve the reference to the hash
my $access_ref = $session->param("access");
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Once you have the reference to the hash back, you can use it to access the data:

# access the data in the hash reference
print "My data from the hash is: ", $access_ref->{hashkey}, "\n";
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Replace "hashkey" above with an actual hash key. See if that works for you.