If you have the DBI module installed, this error is usually caused by binary incompatibilities. Check that all your modules were compiled with the same Perl version that mod_perl was built with. For example, Perl 5.005 and 5.004 are not binary compatible by default.

Other known causes of this problem are:

The solution to these problems is to rebuild Perl and any extension modules from a fresh source tree. Read Perl's INSTALL document for more details.

On the Solaris OS, if you see the "Can't load DBI" or a similar error for the IO module (or whatever dynamic module mod_perl tries to pull in first), you need to reconfigure, rebuild, and reinstall Perl and any dynamic modules. When Configure asks for "additional LD flags," add the following flags:

-Xlinker --export-dynamic

or:

-Xlinker -E

This problem is known to be caused only by installing GNU ld under Solaris.