The error is pretty explicit. $newMember is undef.

You can either check that the $newMember is defined before calling a method on it: warn "Error while archiving file $fileName to $newName" and return unless defined $newMember
or catch the error with an eval eval { $newMember->desiredCompressionLevel($compressionLevel); 1; } or warn "Error for file $fileName, $newName : $@" and return;

eval will return the last instruction (here 1) if it executes correctly or undef if an error is raised. So with the idiom eval { THING; 1; } a true value will be returned on success. 

eval { THING };
warn if $@;

[download]
does the same thing by checking the state of the variable $@.

Once you have found which file is a problem, you'll have to find out why newFromFile() returns undef in that case.

In reply to Re: Perl Archiving Process error by Eily
in thread Perl Archiving Process error by Anonymous Monk

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.