[database] ORA-12528: TNS Listener: all appropriate instances are blocking new connections. Instance "CLRExtProc", status UNKNOWN

I'm getting this error if i try to login as db user. If lsnrctl status is run i get the below error.
DB was working fine all these years and stopped working suddenly.

Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=ABC.LOCAL)(PORT=1521)
STATUS of the LISTENER
------------------------
Alias                     LISTENER
Version                   TNSLSNR for 64-bit Windows: Version 11.2.0.1.0 - Production
Start Date                19-MAY-2014 12:18:17
Uptime                    0 days 0 hr. 22 min. 51 sec
Trace Level               off
Security                  ON: Local OS Authentication
SNMP                      OFF
Listener Parameter File   D:\Oracle\Administrator\product\11.2.0\dbhome_1\network\admin\listener.ora
Listener Log File         d:\oracle\administrator\diag\tnslsnr\abc\listener\alert\log.xml
Listening Endpoints Summary...
  (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=ABC.LOCAL)(PORT=1521)))
  (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(PIPENAME=\\.\pipe\EXTPROC1521ipc)))
Services Summary...
Service "CLRExtProc" has 1 instance(s).
  Instance "CLRExtProc", status UNKNOWN, has 1 handler(s) for this service...
Service "devdb" has 1 instance(s).
  Instance "devdb", status BLOCKED, has 1 handler(s) for this service...
Service "testdb" has 1 instance(s).
  Instance "testdb", status BLOCKED, has 1 handler(s) for this service...
The command completed successfully

If you are using 11G XE with Windows, along with tns listener restart, make sure Windows Event Log service is started.

set ORACLE_SID=<YOUR_SID>
sqlplus "/as sysdba"
alter system disable restricted session;

or maybe

shutdown abort;

or maybe

lsnrctl stop

lsnrctl start

I had this error message with boot2docker on windows with the docker-oracle-xe-11g image (https://registry.hub.docker.com/u/wnameless/oracle-xe-11g/).

The reason was that the virtual box disk was full (check with boot2docker.exe ssh df). Deleting old images and restarting the container solved the problem.

I had this problem on my developent environment with Visual Studio.

What helped me was to Clean Solution in Visual Studio and then do a rebuild.