The flasher refused to flash your Proxmark3? Are there any messages in *red*? The most common reason is that the Proxmark3 RDV4 firmware recently got a new bootloader able to handle larger firmwares and... the image grew over 256k almost at the same time. So your old bootloader can't flash such new images. But it's easy, you just need to flash *first* the bootloader *only*, then the image.
The most common reason of a flashing failure is the interference of ModemManager, read carefully [how to avoid ModemManager-related issues](/doc/md/Installation_Instructions/ModemManager-Must-Be-Discarded.md) and fix your setup!
Another possibility is if, when using the button for entering bootloader mode, the button was released during flashing (for old bootloaders) or the button was pressed again during flashing (for newer bootloaders).
### Determine if the bootloader was damaged or only the main OS image
Unplug, press the Proxmark3 button and keep it pressed when you plug it on USB. If the red LEDs show a "off/on/off/on" pattern, you're goot, you manually entered into the bootloader mode.
On new bootloaders, you can release the button. If the pattern disappears, you're on an older bootloader and you've to do it again and keep the button pressed during all the flashing operation.
You should be back on tracks now. In case the flasher complains about bootloader version, you can follow the button procedure and flash first your bootloader.
The RDV4 firmware can run on other Proxmark3 as such but the booting procedure is a bit slower because of the absence of SIM and external flash.
Make sure to configure properly your `Makefile.platform` to get a firmware better tuned for your Proxmark3 hardware.
See [details here](/doc/md/Use_of_Proxmark/4_Advanced-compilation-parameters.md).
## Troubles with SIM card reader
(RDV4 only) Make sure you've the latest SIM firmware according to the [configuration documentation](/doc/md/Use_of_Proxmark/2_Configuration-and-Verification.md#verify-sim-module-firmware-version).
## Troubles with t5577 commands or MFC/iClass/T55x7 dictionaries
(RDV4 only) Make sure you've set everything up according to the [configuration documentation](/doc/md/Use_of_Proxmark/2_Configuration-and-Verification.md#first-things-on-your-rdv40).
Instructions evolve over time so check if you're still up to date!
pm3 --> sc upgrade f /usr/local/share/proxmark3/firmware/sim011.bin
<>
pm3 --> sc upgrade f /usr/share/proxmark3/firmware/sim011.bin
```
If you didn't install the PRoxmark but you're working from the sources directory and depending how you launch the client, your working directory might be the root of the repository:
If you get warnings related to pixmap or pixbuf such as *Pixbuf theme: Cannot load pixmap file* or *Invalid borders specified for theme pixmap*, it's a problem of your Theme, try another one and the problem should vanish. See e.g. [#354](https://github.com/RfidResearchGroup/proxmark3/issues/354) (Yaru theme on Ubuntu) and [#386](https://github.com/RfidResearchGroup/proxmark3/issues/386) (Kali-X theme on Kali).
It's needed to have a good USB cable to connect Proxmark3 to USB. If you have stability problems (Proxmark3 resets, firmware hangs, especially firmware hangs just after start, etc.)
- check your cable with a USB tester (or try to change it). It needs to have a resistance smaller or equal to 0.3 Ohm.