I've just installed v5.42.0 via Perlbrew using the commands shown under Quickstart:

To install the latest stable release ...

perlbrew install perl-5.42.0
perlbrew switch perl-5.42.0
[download]

I'm guessing your "perlbrew install stable" would achieve the same result.

I've also installed a number of modules, via the cpan utility, including namespace::clean. I repeated your commands:

ken@titan ~/tmp
$ perl -E 'use namespace::clean'

ken@titan ~/tmp
$ perl -v

This is perl 5, version 42, subversion 0 (v5.42.0) built for cygwin-th
+read-multi

Copyright 1987-2025, Larry Wall
...
[download]

So, there's nothing inherently wrong with the perl-5.42.0 from Perlbrew. I acknowledge that you're using Linux and I'm using Cygwin — for test commands as simple as the ones above, I don't believe this would make any difference.

It is a fairly common mistake to copy modules from one Perl version to another; for instance, I might have tried:

ken@titan ~/perl5/perlbrew/perls
$ cp perl-5.40.0/lib/site_perl/5.40.0/namespace/clean.pm perl-5.42.0/l
+ib/site_perl/5.42.0/namespace/clean.pm
[download]

Had I done so, I could have expected an error such as you're getting. I don't know if this is what you've done but your results are suggesting something like this has occurred. Here's some basic information:

• Modules with a compilation requirement cannot be copied successfully to a new Perl version — you must recompile them (installing from CPAN does this for you).
• Modules which appear to be pure Perl may have dependencies with a compilation requirement — see previous point.
• Very simple pure Perl modules with no dependencies can probably be copied safely; however, it's likely to be easier to reinstall from CPAN than going to the trouble of checking source code.

I note ibm1620 suggested clone-modules. I've never used that but it may suit your needs. See perlbrew: COMMAND: CLONE-MODULES for documentation.

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