NBServerMigrator: Migration fails in crosscheck_catalog module with missingdbfiles.txt or missingfiles.txt

Problem

Migration fails in crosscheck_catalog module

Error Message

------------------------------------
[START] crosscheck_catalog
------------------------------------
[INFO] Checking that all files from source are on the target
[INFO] Changing directory /usr/openv/netbackup/tempdb/source
[WARN] db/mds.db is not on the target
[WARN] db/rb.db is not on the target
[WARN] db/jobs/pempersist2 is not on the target
[WARN]
##################################
# A C T I O N    R E Q U I R E D #
##################################
[WARN] There are files missing in the target folder /usr/openv/netbackup/tempdb/source.
The file /usr/openv/nbsm/temp/missingdbfiles.txt lists missing files in target
[WARN] missingfile db exists.. Exiting

Cause

N/A

Solution

Open the missingdbfiles.txt.
1)  If the contents are:
db/mds.db
db/mds.db-journal
db/rb.db
db/rb.db-journal
db/jobs/pempersist2

These files will get created on the Target Primary server once the NetBackup operations are started. Hence we can ignore these missing files.

Do the following:
a) Delete the file missingdbfiles.txt
b) create a touchfile SKIP_crosscheck_catalog in the path <nbsm_folder_path>/temp/
c) Resume migration/data_transfer

For migration:
nbsm_target -overwrite -keep_src_cert -resume

For data_transfer:
nbsm_target -data_transfer -resume

2) If the content of the missingdbfiles.txt is anything apart from the files mentioned in point 1, then it needs to be investigated from NBServerMigrator logs.

The following steps can be taken:
a) Manually copy the missing db files from the Source Primary server to the appropriate path in the Target Primary server.
b) Delete the file missingdbfiles.txt.
c) Re-initiate the data_transfer from the Target Primary server.

Note: 
A similar issue occurs when missingfiles.txt is created during the crosscheck_catalog module.
1) Check the contents of the file and see if the files mentioned are of size 0KB on the source primary server or if they are not accessible on the source primary server.
If yes, do the following:
a) Delete the file missingfiles.txt
b) create a touch file SKIP_crosscheck_catalog in the path <nbsm_folder_path>/temp/
c) Resume migration/data_transfer

2) If the files mentioned inside missingfiles.txt are of size greater than 0KB on the source primary server and the files are accessible, then the following steps can be taken:
a) Manually copy the missing files from the Source Primary server to the appropriate path in the Target Primary server.
b) Delete the file missingfiles.txt.
c) Re-initiate the data_transfer from the Target Primary server.