Avamar: SQL Backup fail with the error "A log gap was identified, or a full backup was not found"

The SQL backup is randomly failing with a log gap error "A log gap was identified, or a full backup was not found."

The corresponding portion from the backup log (with debug):

2022/05/04-23:00:22.18499 [avsql_assist] <=== avsql_assist::evaluate_backup_lsn
2022/05/04-23:00:22.18499 [avsql_assist] ===> sqlconnectimpl_smo::get_last_backup_lsn
2022/05/04-23:00:22.18499 [avsql_assist] retrieving last backup lsn for '<DB_NAME>' db from sys.database_recovery_status
2022/05/04-23:00:22.18499 [avsql_assist] ===> sqlconnectimpl_smo::InitDll
2022/05/04-23:00:22.18499 [avsql_assist] SMO dll already loaded.
2022/05/04-23:00:22.18600 [avsql_assist] <=== sqlconnectimpl_smo::InitDll
2022/05/04-23:00:22.19000 [avsql_assist] ==> SMOWrap::SMO_GetLastBackupLSN
2022/05/04-23:00:22.19000 [avsql_assist] database '<DB_NAME>', last backup lsn = '271000002085600001'
2022/05/04-23:00:22.19099 [avsql_assist] <=== sqlconnectimpl_smo::get_last_backup_lsn
2022/05/04-23:00:22.19099 [avsql_assist] ===> avsql_metadata::get
2022/05/04-23:00:22.19099 [avsql_assist] ===> avsql_metadata::get
2022/05/04-23:00:22.19099 [avsql_assist] <=== avsql_metadata::get
2022/05/04-23:00:22.19099 [avsql_assist] <=== avsql_metadata::get
2022/05/04-23:00:22.19099 [avsql_assist] Last backup LSN: '', Current LSN: '271000002085600001'
2022/05/04-23:00:22.19099 [avsql_assist] ===> avsql_assist::align_numeric_ustrings
2022/05/04-23:00:22.19099 [avsql_assist] Before alignment - Str1: '', Str2: '271000002085600001'
2022/05/04-23:00:22.19099 [avsql_assist] After alignment - Str1: '000000000000000000', Str2: '271000002085600001'
2022/05/04-23:00:22.19099 [avsql_assist] <=== avsql_assist::align_numeric_ustrings
2022/05/04-23:00:22.19099 [avsql_assist] Aligned before compare- Last backup (metadata) LSN: '000000000000000000', Current (SQL Server) LSN: '271000002085600001'
2022-05-04 19:00:22 avsql Info <15765>: A log gap was identified or a full backup was not found.

The problem is parsing the sqlmeta file from the previous incremental backup.

The bottom portion of the sqlmeta file (exists in system_info area files - see KB 000102778 Avamar - How to retrieve the system_info area files from an Avamar backup

<file file_type="Rows Data" physical_path="<DB_PATH>.ndf" 
          logical_name="<DB_PATH>" />
          <file file_type="Rows Data" physical_path="<DB_PATH>.ndf"
          logical_name="<DB_PATH>" />
          <file file_type="Rows Data" physical_path="<DB_PATH>.ndf" 
          logical_name="<DB_PATH>" />
          <file file_type="Rows Data" physical_path="<DB_PATH>.ndf" 
          logical_name="<DB_PATH>" />
          <file f

***** FILE TRUNCATED FROM 17411017 TO 16777216 BYTES *****

The sqlmeta file was truncated due to avtar size limitation 16 MB.
The SQL Server in question has multiple databases. Each database has multiple file groups, which caused a file (sqlmeta) to have more than 90 thousand rows (16+ MB size). 

To resolve this issue "A log gap was identified, or a full backup was not found." apply the corresponding engineering Hotfix:

• For the software release 19.8.100-83 apply the HF 338735
• For the software release 19.9.100-78 apply the HF 338736

 

• Follow this KB article to download the HF and remember to read the README file instructions before applying it:
  • KB  000102778 - Avamar: How to find and download a product hotfix, patch, install or upgrade package from the Dell Support website