Put use FileHandle; at the top of the module that is producing the errors. Some older perls don't load it automatically.

Example:

$ perl -E 'open $fh, "<a.txt"; $fh->seek(0, 0);'
Can't locate object method "seek" via package "IO::Handle" at -e line 
+1.
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$ perl -MFileHandle -E 'open $fh, "<a.txt"; $fh->seek(0, 0);'
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Or, depending on the code in question (you don't specify where it is), you could use the seek function instead (no need for FileHandle):

seek $fh, 0, 0;
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