The fact that asterisk didn't start was unrelated to this problem (had installed external modules that didn't match the new version 11).
But contrary to OP the modules cannot be loaded by hand. The same error appears:
com01*CLI> module load app_stack.so
Unable to load module app_stack.so
Command 'module load app_stack.so' failed.
[May 25 16:35:46] WARNING[5474]: loader.c:423 load_dynamic_module: Error loading module 'app_stack.so': /usr/lib/asterisk/modules/app_stack.so: undefined symbol: ast_agi_unregister
[May 25 16:35:46] WARNING[5474]: loader.c:902 load_resource: Module 'app_stack.so' could not be loaded.
The fact that asterisk didn't start was unrelated to this problem (had installed external modules that didn't match the new version 11).
But contrary to OP the modules cannot be loaded by hand. The same error appears:
com01*CLI> module load app_stack.so module: Error loading module 'app_stack.so': /usr/lib/ asterisk/ modules/ app_stack. so: undefined symbol: ast_agi_unregister
Unable to load module app_stack.so
Command 'module load app_stack.so' failed.
[May 25 16:35:46] WARNING[5474]: loader.c:423 load_dynamic_
[May 25 16:35:46] WARNING[5474]: loader.c:902 load_resource: Module 'app_stack.so' could not be loaded.