"panic: Fatal: tried to backup more data than specified size!" when doing disk backup

[KlugFR]

Hello.

I tried to do a backup yesterday and it failed with the error in the title.
Data is uploaded but at the end something goes wrong.

I tried again a bit later, same error.
Here's a log snippet of the second try:

C:\Temp>pbsmachinebackup.exe -authid "relay@pbs!api" -secret "1ff29973-xxxx-4684-a5b8-xxxxx" -backupdev "\\.\PhysicalDrive0" -baseurl "https://192.168.88.164:8007" -certfingerprint "11:f0:b8:38:03:d1:3a:48:a0:e3:b8:ca:61:d5:91:79:74:be:xxxx" -datastore "Relay" -type vm
\\?\Volume{bc7dfc19-0000-0000-0000-100000000000}\
\\?\Volume{6edad51a-1de8-4647-a9ce-74efc04d62f4}\
\\?\Volume{bc7dfc19-0000-0000-0000-501f00000000}\
Part: 1 1MB 500MB
Part: 2 501MB 2047GB
Creating VSS Snapshot...Snapshot created: {F7EA1473-7FA4-4244-A4B5-4819E31F839B}
Symlink from:  \\?\GLOBALROOT\Device\HarddiskVolumeShadowCopy16\  to:  C:\Users\Administrator\AppData\Roaming\PBSBackupGO\VSS\{F7EA1473-7FA4-4244-A4B5-4819E31F839B}
[{StartByte:0 EndByte:1048576 RequiresVSS:false Skip:false Letter:} {StartByte:1048576 EndByte:525336576 RequiresVSS:false Skip:false Letter:} {StartByte:525336576 EndByte:2199023255552 RequiresVSS:true Skip:false Letter:C}]
Partition: 0
Partition: 1
backup-id=WHS&backup-time=1779782840&backup-type=vm&store=Relay
Reading response to upgrade...
Upgraderesp: HTTP/1.1 101 Switching Protocols
connection: upgrade
upgrade: proxmox-backup-protocol-v1
date: Tue, 26 May 2026 08:07:43 GMT


Successfully upgraded to HTTP/2.
Failed to read FIDX Header
Cannot get previous: unexpected EOF
Chunk size min is 1048576 , max 16777216
Writer id:  1
Chunk 1/512000/0
Chunk 2/512000/0
Chunk 3/512000/0
Chunk 4/512000/0
Chunk 5/512000/0
Chunk 6/512000/0
Chunk 7/512000/0
Chunk 8/512000/0
Chunk 9/512000/0
Chunk 10/512000/0
.../...
Chunk 511997/512000/245938
Chunk 511998/512000/245939
Chunk 511999/512000/245940
Chunk 512000/512000/245941
panic: Fatal: tried to backup more data than specified size!

goroutine 1 [running]:
main.main()
        /home/runner/work/proxmoxbackupclient_go/proxmoxbackupclient_go/machinebackup/main.go:329 +0xa32

[tizbac]

Can you confirm partition is not ending beyond last lba? Il giorno mar 26 mag 2026 alle ore 10:11 KlugFR ***@***.***> ha scritto:

…

*KlugFR* created an issue (tizbac/proxmoxbackupclient_go#72) <#72> Hello. I tried to do a backup yesterday and it failed with the error in the title. Data is uploaded but at the end something goes wrong. I tried again a bit later, same error. Here's a log snippet of the second try: ''' C:\Temp>pbsmachinebackup.exe -authid ***@***.***!api" -secret "1ff29973-xxxx-4684-a5b8-xxxxx" -backupdev "\.\PhysicalDrive0" -baseurl " https://192.168.88.164:8007" -certfingerprint "11:f0:b8:38:03:d1:3a:48:a0:e3:b8:ca:61:d5:91:79:74:be:xxxx" -datastore "Relay" -type vm \?\Volume{bc7dfc19-0000-0000-0000-100000000000} \?\Volume{6edad51a-1de8-4647-a9ce-74efc04d62f4} \?\Volume{bc7dfc19-0000-0000-0000-501f00000000} Part: 1 1MB 500MB Part: 2 501MB 2047GB Creating VSS Snapshot...Snapshot created: {F7EA1473-7FA4-4244-A4B5-4819E31F839B} Symlink from: \?\GLOBALROOT\Device\HarddiskVolumeShadowCopy16\ to: C:\Users\Administrator\AppData\Roaming\PBSBackupGO\VSS{F7EA1473-7FA4-4244-A4B5-4819E31F839B} [{StartByte:0 EndByte:1048576 RequiresVSS:false Skip:false Letter:} {StartByte:1048576 EndByte:525336576 RequiresVSS:false Skip:false Letter:} {StartByte:525336576 EndByte:2199023255552 RequiresVSS:true Skip:false Letter:C}] Partition: 0 Partition: 1 backup-id=WHS&backup-time=1779782840&backup-type=vm&store=Relay Reading response to upgrade... Upgraderesp: HTTP/1.1 101 Switching Protocols connection: upgrade upgrade: proxmox-backup-protocol-v1 date: Tue, 26 May 2026 08:07:43 GMT Successfully upgraded to HTTP/2. Failed to read FIDX Header Cannot get previous: unexpected EOF Chunk size min is 1048576 , max 16777216 Writer id: 1 Chunk 1/512000/0 Chunk 2/512000/0 Chunk 3/512000/0 Chunk 4/512000/0 Chunk 5/512000/0 Chunk 6/512000/0 Chunk 7/512000/0 Chunk 8/512000/0 Chunk 9/512000/0 Chunk 10/512000/0 .../... Chunk 511997/512000/245938 Chunk 511998/512000/245939 Chunk 511999/512000/245940 Chunk 512000/512000/245941 panic: Fatal: tried to backup more data than specified size! goroutine 1 [running]: main.main() /home/runner/work/proxmoxbackupclient_go/proxmoxbackupclient_go/machinebackup/main.go:329 +0xa32 ''' — Reply to this email directly, view it on GitHub <#72?email_source=notifications&email_token=AABBV6V6POXLIZUWGC7UXCL44VGR5A5CNFSL4Z3JMQ5C6L3HNF2C22DVMIXUS43TOVSS6NBVGIZDKNRVHAZDBJTSMVQXG33OVJZXKYTTMNZGSYTFMSSWK5TFNZ2KYZTPN52GK4S7MNWGSY3L>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AABBV6W3ZPI2J77FVRD64LT44VGR5AVCNFSM6AAAAACZNIAZLOVHI2DSMVQWIX3LMV43ASLTON2WKOZUGUZDENJWGU4DEMA> . Triage notifications on the go with GitHub Mobile for iOS <https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> or Android <https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub>. You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>

[KlugFR]

How do I do this?

[KlugFR]

I've tried TestDisk and it confirms there's something wrong.

Disk \\.\PhysicalDrive0 - 2147 GB / 2000 GiB - CHS 261083 255 63
The hard disk (2147 GB / 2000 GiB) seems too small! (< 2199 GB / 2047 GiB)
Check the hard disk size: HD jumper settings, BIOS detection...
The following partition can't be recovered:
     Partition               Start        End    Size in sectors
>  HPFS - NTFS             63 221 31 267349  89  4 4293941248

I'm actually trying to get rid of a Windows Server (physical one) and make it a VM (it's the only Windows computer I have) and wanted to use ProxmoxBackupClient for this job (backup to PBS then restore to VM, good old P2V).
Looks like I have to find another way of doing this.

[tizbac]

something is very wrong, partition is 2x the disk size, you can try ( dangerous ) to fix it using parted to end at the end of disk, beware also that if you can boot linux on that server physically you can also use clonezilla in lite server mode for the purpose :) Also in mine restore on virtual still broken didn't have time to fix, probably something stupid in the manifest Il giorno mar 26 mag 2026 alle ore 18:05 KlugFR ***@***.***> ha scritto:

…

*KlugFR* left a comment (tizbac/proxmoxbackupclient_go#72) <#72 (comment)> I've tried TestDisk and it confirms there's something wrong. Disk \\.\PhysicalDrive0 - 2147 GB / 2000 GiB - CHS 261083 255 63 The hard disk (2147 GB / 2000 GiB) seems too small! (< 2199 GB / 2047 GiB) Check the hard disk size: HD jumper settings, BIOS detection... The following partition can't be recovered: Partition Start End Size in sectors > HPFS - NTFS 63 221 31 267349 89 4 4293941248 I'm actually trying to get rid of a Windows Server (physical one) and make it a VM (it's the only Windows computer I have) and wanted to use ProxmoxBackupClient for this job (backup to PBS then restore to VM, good old P2V). Looks like I have to find another way of doing this. — Reply to this email directly, view it on GitHub <#72?email_source=notifications&email_token=AABBV6X5L7LA5KQUPIJ7QH344W6F7A5CNFSNUABFM5UWIORPF5TWS5BNNB2WEL2JONZXKZKDN5WW2ZLOOQXTINJUGU4TMOBXGAZ2M4TFMFZW63VHMNXW23LFNZ2KKZLWMVXHJLDGN5XXIZLSL5RWY2LDNM#issuecomment-4545968703>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AABBV6UM3FDJCRCZ26WGSHD44W6F7AVCNFSM6AAAAACZNIAZLOVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHM2DKNBVHE3DQNZQGM> . Triage notifications on the go with GitHub Mobile for iOS <https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> or Android <https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub>. You are receiving this because you commented.Message ID: ***@***.***>

[KlugFR]

I tried (Free) Veeam Backup Agent a couple of hours ago (to avoid rebooting 8-)).
Same kind of error, it told me the partition was something like 60 GB too big for the underlying disk so I stopped it.
There's a KB suggesting to shrink the partition so I did.
Now trying again to backup with ProxmoxBackupClient, I'll let you know the results.

[tizbac]

Ok, to restore use pbsnbd + clonezilla and not directly PVE because for now I have to fix it Il mer 27 mag 2026, 15:57 KlugFR ***@***.***> ha scritto:

…

*KlugFR* left a comment (tizbac/proxmoxbackupclient_go#72) <#72 (comment)> I tried (Free) Veeam Backup Agent a couple of hours ago (to avoid rebooting 8-)). Same kind of error, it told me the partition was something like 60 GB too big for the underlying disk so I stopped it. There's a KB suggesting to shrink the partition so I did. Now trying again to backup with ProxmoxBackupClient, I'll let you know the results. — Reply to this email directly, view it on GitHub <#72?email_source=notifications&email_token=AABBV6QZT5UPSGI7ZXNJ7PT443X5XA5CNFSNUABFM5UWIORPF5TWS5BNNB2WEL2JONZXKZKDN5WW2ZLOOQXTINJVGUYTQNZZGM32M4TFMFZW63VHMNXW23LFNZ2KKZLWMVXHJLDGN5XXIZLSL5RWY2LDNM#issuecomment-4555187937>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AABBV6RMAKOGOF5BI2LRVUT443X5XAVCNFSM6AAAAACZNIAZLOVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHM2DKNJVGE4DOOJTG4> . Triage notifications, keep track of coding agent tasks and review pull requests on the go with GitHub Mobile for iOS <https://github.com/notifications/mobile/ios/AABBV6V2SF7SH7IDSS3VO33443X5XA5CNFSNUABFM5UWIORPF5TWS5BNNB2WEL2JONZXKZKDN5WW2ZLOOQXTINJVGUYTQNZZGM32M4TFMFZW63VHMNXW23LFNZ2KKZLWMVXHJKTGN5XXIZLSL5UW64Y> and Android <https://github.com/notifications/mobile/android/AABBV6W26GNBZVERVHU2IOD443X5XA5CNFSNUABFM5UWIORPF5TWS5BNNB2WEL2JONZXKZKDN5WW2ZLOOQXTINJVGUYTQNZZGM32M4TFMFZW63VHMNXW23LFNZ2KKZLWMVXHJLTGN5XXIZLSL5QW4ZDSN5UWI>. Download it today! You are receiving this because you commented.Message ID: ***@***.***>

[KlugFR]

It failed with another error:

Chunk 511999/512000/248806
Chunk 512000/512000/248807
panic: strconv.ParseInt: parsing "": invalid syntax

goroutine 1 [running]:
main.main()
        /home/runner/work/proxmoxbackupclient_go/proxmoxbackupclient_go/machinebackup/main.go:374 +0xa11

[tizbac]

Use backup type host and not VM please , i will fix that asap Il giorno mer 27 mag 2026 alle ore 18:36 KlugFR ***@***.***> ha scritto:

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*KlugFR* left a comment (tizbac/proxmoxbackupclient_go#72) <#72 (comment)> It failed with another error: Chunk 511999/512000/248806 Chunk 512000/512000/248807 panic: strconv.ParseInt: parsing "": invalid syntax goroutine 1 [running]: main.main() /home/runner/work/proxmoxbackupclient_go/proxmoxbackupclient_go/machinebackup/main.go:374 +0xa11 — Reply to this email directly, view it on GitHub <#72?email_source=notifications&email_token=AABBV6UFXRZRS4EMD4DMRJ3444KRVA5CNFSNUABFM5UWIORPF5TWS5BNNB2WEL2JONZXKZKDN5WW2ZLOOQXTINJVGY2TMMJQGE22M4TFMFZW63VHMNXW23LFNZ2KKZLWMVXHJLDGN5XXIZLSL5RWY2LDNM#issuecomment-4556561015>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AABBV6QHSQYKMHIZWCHIVWT444KRVAVCNFSM6AAAAACZNIAZLOVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHM2DKNJWGU3DCMBRGU> . Triage notifications, keep track of coding agent tasks and review pull requests on the go with GitHub Mobile for iOS <https://github.com/notifications/mobile/ios/AABBV6SC5YT4IXXBQP45HPL444KRVA5CNFSNUABFM5UWIORPF5TWS5BNNB2WEL2JONZXKZKDN5WW2ZLOOQXTINJVGY2TMMJQGE22M4TFMFZW63VHMNXW23LFNZ2KKZLWMVXHJKTGN5XXIZLSL5UW64Y> and Android <https://github.com/notifications/mobile/android/AABBV6TQNAJDJESRLQLWFQ3444KRVA5CNFSNUABFM5UWIORPF5TWS5BNNB2WEL2JONZXKZKDN5WW2ZLOOQXTINJVGY2TMMJQGE22M4TFMFZW63VHMNXW23LFNZ2KKZLWMVXHJLTGN5XXIZLSL5QW4ZDSN5UWI>. Download it today! You are receiving this because you commented.Message ID: ***@***.***>