Below messages are seen in the logs of SRX device:

Oct 8 19:08:58 SRX ffp[9409]: pdb_sync_master_cleanup: could not stat /var/pdb/profile_sync_start, errno: 2

Oct 8 19:08:58 SRX ffp[9409]: pdb_sync_master_cleanup: could not stat /var/pdb/profile_sync_done, errno: 2

Oct 8 19:11:20 SRX ffp[9436]: pdb_sync_master_cleanup: could not stat /var/pdb/profile_sync_start, errno: 2

Oct 8 19:11:20 SRX ffp[9436]: pdb_sync_master_cleanup: could not stat /var/pdb/profile_sync_done, errno: 2

These are syslog debug-level messages from a cleanup operation indicating there were no synchronization files to remove/cleanup.  

This debug message is observed when the files pdb_sync_start and pdb_sync_done do not exist during pdb_sync_master_cleanup. The files shall be present only when the pdb synchronization is in progress at the same time. 

This is not an error but an expected debug message. The messages are useful if there is a problem during the commit.

These messages have no functional impact and can be ignored.

To stop seeing these messages, refer to KB9382 - How to prevent syslog messages from being written to the log file [juniper.net] .