Messed up storage don't know how to fix it

[WayneKosi]

A while ago I had a ROM running but switched back to OOS due to battery drain. Time passed and I wanted to give it another go and tried installing another ROM, after getting the recommended variant of TWRP running I tried doing the usual, wiping then installing, but as soon as I tried flashing the ROM it kept giving me this log:

Flashing A/B zip to inactive slot: A
Step 1/2
Error applying update: 26 (ErrorCode :: kDownloadMetadataSignatureMismatch) 
Updater process ended with ERROR: 1
To flash additional zips, please reboot recovery to switch to the updated slot. 
Error installing zip file '/sdcard/<insert filename>.zip'

etc

I thought maybe it was because the ROM had failed to download properly, so I tried a different ROM and downloaded the other one again, but it still gave me the same error. I tried several things like formatting the storage because I saw a youtube video doing that, but although my phone boots normally if I try to download anything it fails. Not sure why this is happening. I still can't flash any ROM.

 

[Psk.It]

If partitions have been corrupt
I think you have hetter to flash latest "oos fastboot"
then restart from a "kind new" phone

anyway,
tipically with .zip file, also a .md5 or .md5sum file Is published
if you start checking It, you will not run in this kind of problems

 

[Coolaaron88]

A while ago I had a ROM running but switched back to OOS due to battery drain. Time passed and I wanted to give it another go and tried installing another ROM, after getting the recommended variant of TWRP running I tried doing the usual, wiping then installing, but as soon as I tried flashing the ROM it kept giving me this log:

Flashing A/B zip to inactive slot: A
Step 1/2
Error applying update: 26 (ErrorCode :: kDownloadMetadataSignatureMismatch) 
Updater process ended with ERROR: 1
To flash additional zips, please reboot recovery to switch to the updated slot. 
Error installing zip file '/sdcard/<insert filename>.zip'

etc

I thought maybe it was because the ROM had failed to download properly, so I tried a different ROM and downloaded the other one again, but it still gave me the same error. I tried several things like formatting the storage because I saw a youtube video doing that, but although my phone boots normally if I try to download anything it fails. Not sure why this is happening. I still can't flash any ROM.

Long shot but did you figure this issue out? Im running into the same issue with my Oneplus 7 Pro