Upgrade indexes from 32 bit to 64 bit failed in EV 12.4.1

Hello,

We are starting the process of upgrading indexes from 32 bit to 64 bit EV version 12.4.1.

During upgrade on some indexes we received the following error:

"Some of indexes failed to upgrade with error:

The upgrade subtask has failed.
Error Code: 60
Description:Too many failed consecutive items
Error encountered whilst trying to fetch item Sequence Number '1279' Item Identifier '201109176268949~201107121404040000~Z~90B73BA3D77FFF16FE751163C66AEBB1'
Error encountered whilst trying to fetch item Sequence Number '1280' Item Identifier '201109176268949~201107130247530000~Z~90B734D01D2FCC9118F9DB9F75315471'
Error encountered whilst trying to fetch item Sequence Number '1281' Item Identifier '201109176268948~201107121304460000~Z~90B7353FD4E841FB408A0BC0E437B8F1'
Error encountered whilst trying to fetch item Sequence Number '1282' Item Identifier '201109176268949~201107130959030000~Z~90B7323CB2DCA70E108E2450C40BD561'
Error encountered whilst trying to fetch item Sequence Number '1283' Item Identifier '201109176268950~201107140520000000~Z~90B733256B97AFF0CE90847CBD041EF1'
Error encountered whilst trying to fetch item Sequence Number '1284' Item Identifier '201109176268949~201107131239250000~Z~90B73FAC09FD00330CAA0A8542284871'
Error encountered whilst trying to fetch item Sequence Number '1285' Item Identifier '201109176268950~201107150253140000~Z~90B7338119EF2D722DE4A5DB16A4A461'
Error encountered whilst trying to fetch item Sequence Number '1286' Item Identifier '201109176268951~201107150334150000~Z~90B74EE4ACF55F1934047150A9D2F791'
Error encountered whilst trying to fetch item Sequence Number '1287' Item Identifier '201109176268952~201107150537160000~Z~90B73ECF68EA02D37925725059C95891'
Error encountered whilst trying to fetch item Sequence Number '1288' Item Identifier '201109176268952~201107150540200000~Z~90B73A102B43DE954879B6BBA65EC151'
Error encountered whilst trying to fetch item Sequence Number '1289' Item Identifier '201109176268953~201107150540340000~Z~90B735E17C9598E3C8FD6F9072899B71'
Error encountered whilst trying to fetch item Sequence Number '1290' Item Identifier '201109176268953~201107150541540000~Z~90B7304BF18210EF998B37F381BD9F01'
Error encountered whilst trying to fetch item Sequence Number '1291' Item Identifier '201109176268955~201107150622450000~Z~90B73F07EB7E1749059901E60F94A331'
Error encountered whilst trying to fetch item Sequence Number '1292' Item Identifier '201109176268957~201107160422220000~Z~90B73BC555AF6E8A3E12F8456597A7B1'
Error encountered whilst trying to fetch item Sequence Number '1293' Item Identifier '201109176268956~201107150938340000~Z~90B733562BF96B8A9116BFFC60126661'
Error encountered whilst trying to fetch item Sequence Number '1294' Item Identifier '201109176268957~201107160423550000~Z~90B73922FA4A46F42BBE46616F8B05D1'
Error encountered whilst trying to fetch item Sequence Number '1295' Item Identifier '201109176268959~201107161036300000~Z~90B73EB67843444F6921F6B6E76BAC11'
Error encountered whilst trying to fetch item Sequence Number '1296' Item Identifier '201109176268959~201107161036300000~Z~90B736AD834A46A93BDE70EDAFD25201'
Error encountered whilst trying to fetch item Sequence Number '1297' Item Identifier '201109176268963~201107180727320000~Z~90B73477D80FE98113DF30F6155DA0F1'
Error encountered whilst trying to fetch item Sequence Number '1298' Item Identifier '201109176268961~201107180613400000~Z~90B73478E71B2AC8A04E15E31EF79161'
Error encountered whilst trying to fetch item Sequence Number '1299' Item Identifier '201109176268964~201107181414330000~Z~90B738D33572F305CA26A0B71825C6A1'
Error encountered whilst trying to fetch item Sequence Number '1300' Item Identifier '201109176268965~201107191003040000~Z~90B73F10494065120594227C86C1A3B1'
Error encountered whilst trying to fetch item Sequence Number '1301' Item Identifier '201109176268965~201107191156320000~Z~90B7397C18139037A4D2F0C5F3421F51'
Error encountered whilst trying to fetch item Sequence Number '1302' Item Identifier '201109176268965~201107191310230000~Z~90B73363659E0FAFB0F6B06613019191'
Error encountered whilst trying to fetch item Sequence Number '1303' Item Identifier '201109176268967~201107210430420000~Z~90B73DCCE954AA4A2E5D991643F3DF41'

For more information, see the online index troubleshooting technical note at:

http://www.veritas.com/docs/TECH160420

Check the event logs on the Storage service computer for additional information."

And process was failed.

Data mentioned in the error cannot be restored because it was lost in first pahse of implementation (many years ago).

Could you please let me know the decision how to resolve it?

Thank you in advance.