Cannot access property starting with "\0" in SAML2\XML\saml\NameIDType->__unserialize()

We ran into this issue as well. It seems like existing sessions that were created using saml2 <= 4.6.10 can not be parsed by 4.6.11. We used the mysql option to store sessions. A TRUNCATE of the tables fixed it for us.

(Note: also truncate the Drupal `sessions` table or you end up in an endless redirect loop)

```
--- SimpleSAMLphp database:
TRUNCATE SimpleSAMLphp_kvstore;
TRUNCATE SimpleSAMLphp_saml_LogoutStore;

--- Drupal database:
TRUNCATE sessions;
```

That sounds like a SimpleSAMLphp bug that we can't do anything about.

Thanks @roderickgadellaabsl this seems like a easy way to solve it.
Will try this with the next release cycle of the website we were having the problem with.

Although there is nothing that needs fixing in this module, we can leave this here for other people to find it!

Solution #2 in code:

drush sql-query "TRUNCATE TABLE sessions"
drush sql-query "TRUNCATE TABLE simpleSAMLphp_kvstore"
drush sql-query "TRUNCATE TABLE simpleSAMLphp_saml_LogoutStore"

Hello,
I'm experiencing the same.
SimpleSamlphp is installed with composer as part Drupal

I looked at my databases/tables:

I do not have a " SimpleSAMLphp" database.
and do not have "simpleSAMLphp_kvstore" and "simpleSAMLphp_saml_LogoutStore" tables

however in the Drupal database, I do have:
simplesaml_saml_LogoutStore and
simpleSAMLphp_saml_LogoutStore

Am I missing something?

I do not have a " SimpleSAMLphp" database.

The tables are (probably) in your Drupal database, not a separate one.