MIB SD card or USB not recognised, or firmware update errors from the card

How to recognise the problem

The symptoms fall into two groups: the unit does not see the update at all, or it starts the update and then stops with an error that points at the card.

Media playback from the same USB stick or card can still work while the update option stays greyed out, so a readable card does not prove the update medium is correct.

• SD card or SD1 slot greyed out or not selectable in the software update menu, red engineering menu or developer mode
• Messages such as no update found, update not available, source is not supported, unsupported media, invalid update medium, or no valid update data found
• Update starts, shows logos or searches for data, then stops with an error
• Read and file errors reported by owners: 'Error: File Access, Errorcode: 1', 'cpuboot FileReadError no file', release information or version information file not read, source read error 138, 'Error: SD Card 1', 'Error writing', a no-SWDL error, error 1556
• Checksum or hash errors, including an ifs-root checksum failure
• A Retry/Skip or Retry/Ignore/Cancel prompt partway through, or the unit dropping into the red emergency update screen
• Nothing at all happens when the card is inserted

Likely causes

Owners trace failures to the following causes, roughly in order of how often they come up. More than one can apply at once, for example an exFAT card that also has the files in a subfolder.

• Wrong file system: cards formatted exFAT or NTFS instead of FAT32. Windows only offers exFAT for larger cards, so 64GB and 128GB cards often end up exFAT by default.
• Card too large: several owners report 128GB cards being rejected or greyed out, while 64GB or smaller worked.
• Faulty, cheap, counterfeit or microSD-with-adapter cards causing read errors, hash mismatches and failed or very slow updates.
• Wrong folder layout: the firmware folder copied as a whole instead of its contents, so metainfo2.txt and the firmware folders are not in the card root.
• Archive not extracted: a .zip, .rar or .7z left on the card. The unit does not read archives.
• Corrupt files from a damaged download or a bad extraction. Re-copying the same bad files to new cards reproduces the same error.
• Hidden files written by macOS (for example ._ prefixed files), which can cause hash failures or, on MH2P, a complaint about more than one manifest.
• Firmware that does not match the unit: wrong train or variant, an AIO image used where a standard update was needed, or a metainfo file that does not list the installed train as a supported source.
• Hardware limits: some units cannot take updates by SD card at all (see the section on units that cannot use the SD method).

Before you start

A failed update can leave the unit in emergency mode, so prepare before retrying.

• Note the current train and part number from the service menu.
• Back up coding and adaptations before any update, patch or coding change.
• Keep a stable power supply: owners advise keeping the car on or connected to a proper battery supply and not letting the unit go to sleep during the update.
• Use only firmware that matches the unit's train, variant and part number. Check the metainfo file to confirm the installed train is listed as a supported source.

Fix: work through these steps in order

Most confirmed fixes came from steps 1 to 5. If the update is already stuck on an error screen with a Retry option, read step 7 first.

1. Use a good card. Owners repeatedly confirm that replacing the card fixed the error, including updates from MST2_EU_VW_ZR_P0472T to P0480T and from MHI2_ER_AUG22_s2140. Prefer a genuine full-size SD card from a reputable brand (SanDisk Extreme Pro is named by owners) over a microSD in an adapter. Check the card is not write-protected.
2. Pick a sensible size. 64GB or smaller is the most common advice; 128GB cards were rejected in several reports. One owner only succeeded with a 4GB card, and another found a 32GB card too small for a P310 package on an MHI2Q (error 136) and needed 64GB. If one size fails, try another.
3. Format as FAT32, preferably a full (not quick) format on a Windows PC. For cards over 32GB, Windows will not offer FAT32; owners used GUIformat, a FAT32 Format utility or MiniTool Partition Wizard instead. One confirmed alternative uses diskpart from an administrator command prompt: list and select the card's disk, run clean, create a primary partition (size=27000 was used), assign a letter, select partition 1, then format fs=fat32 quick. Use a single partition: a card or stick split into partitions caused greyed-out menus and interrupted copies.
4. Extract a fresh copy of the firmware to a folder on the computer first (7-Zip or WinRAR), then copy it to the card. If the download reports errors while extracting, download it again. FAT32 cannot hold a single file over 4GB, so extract the contents of a large AIO archive rather than copying the archive itself.
5. Put the contents in the card root. metainfo2.txt and the firmware folders (for example cpu and the other subfolders) must sit directly in the root, not inside a folder named after the train or the platform. On MH2P and MHI3 packages, the DATA and META folders go at the top level. Keep the layout exactly as delivered otherwise, and delete the archive from the card.
6. If you prepared the card on a Mac, remove hidden files before ejecting. Owners used BlueHarvest with its eject-after-cleaning option, or deleted the ._manifest file from the Meta folder. Another option is to stop macOS writing these files with: defaults write com.apple.desktopservices DSDontWriteUSBStores -bool true. Using a Windows PC avoids the issue.
7. If the update stopped at a Retry/Skip or Retry/Ignore/Cancel prompt, do not press anything and do not leave the screen. Remove the card, prepare a new one as above, insert it and press Retry. This is confirmed for MIB2 units going from PQ472T to PQ475T and for MST2 units showing error 1556, where the retry had to be started from the red emergency menu without leaving it.
8. Start the update from the right place. Depending on the unit, owners used the settings update menu, the red engineering menu, or SWDL enabled from the green menu. On a PCM, the update file was only found from the engineering menu, not the user menu. On units with two slots, try SD1 first, then SD2.
9. Restart and retry. Some owners power-cycled the unit or performed an MMI factory reset before retrying; one MST2 owner pulled fuse 12 to reset the unit after moving the files to the root.

Special cases

These situations came up less often but have specific fixes in the notes.

• Units on firmware 01xx or 02xx (older GEM 3.x): owners replaced the cpu folder in the card root with the cpu folder from the M.I.B. toolbox gem folder. Skip this on newer firmware.
• Error 1556 on MST2 (MST2_EU_VW_ZR_P0478T to P0480T): attributed to patched packages that removed the online approval version so the version check fails. Reformatting or replacing the card, rewriting the software and retrying from the red menu worked.
• USB versus SD: on MST2 PQ units, updates are reported to be read only from SD, but a FAT32 USB stick in USB1 has been suggested for firmware when the SD slot is damaged; activators and patches will not work from USB. On MIB3, USB was described as less reliable than SD. Owners disagree on whether USB works for other units; where SD fails on MHI2 due to microSD-only cards, a FAT32 USB stick was suggested.
• Map packages close to card capacity: a 29.1GB MHI2 map package did not fit a 32GB card formatted FAT32 (28.8GB usable); a USB stick was suggested instead.
• M.I.B. toolbox installs: an NTFS card caused an install error on a SEAT MU1447 unit; reformatting as FAT32 fixed it. Patches go inside the PATCH folder in the card root.

Units that cannot use the SD method

Some failures are not a card problem. A greyed-out card on these units will not be fixed by changing the medium.

• Single-slot MIB2/MST2 units (Technisat, STD2Plus) are reported to be excluded from SD installation, for example a 3Q0 035 877A unit on MST2_RoA_VW_ZR_P0245T; owners used USB2HSD, OTG or eMMC methods instead.
• SD installation is reported as not possible on part numbers 5C0035684F and 5F003587* / 5QA035874*.
• An 819C hardware variant was reported to need ODIS rather than an SD card patch.
• Delphi MST2 units are limited to a firmware range (the 2xx range per owners); a higher train such as MST2_EU_VW_P0883D shows the card greyed out.
• A GEM 3.4 MST2 unit (3Q0035864, on MST2_EU_VW_ZR_P0125T) was reported to be limited to the 01xx range by its hardware, though updates within that range by SD are possible.

What did not help or remains unresolved

Some reports were not solved by card changes, and owners should treat these as possible signs of a different fault.

• 'Error writing' across several cards, firmware versions and cluster sizes: re-downloading and reformatting did not help. One suggestion was a failing eMMC in the unit, which is unconfirmed.
• Cards and USB sticks not seen in the update menu while music still played from USB, even with the meta file checked: unresolved.
• An A4 B9 MHS2 US unit that would not install P2037, P1442 or K1240: factory reset and a different card did not help.
• A MIB1 unit stuck in a restart loop after a failed update to 0490 no longer detected the card; no fix was reported.
• Repeating the same error on several new cards usually means the files, not the cards, are bad: re-download and re-extract.
• Cluster size advice varies (default, 1024 bytes, 2KB, 4KB or 8KB were each recommended), and no single value is confirmed as required.