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Troubleshooting the tutorials

Problem 1: How do I enable debug logs?

Please see Error handling and debugging for details.

Problem 2: Client application errors in developer mode

When using the client application in developer mode, you may see one of these errors in your console:

Device not configured for Device Management - exit


fcc_init() failed with Error 12!


Your SD card is corrupted. Please use your computer to format the SD card with the FAT32 filesystem. If the error persists, you may have to use a new SD card.

Problem 3: Device Management Client (or Edge) seems to hang

The application seems to hang in Linux. It does not print out anything or connect, and just freezes. An example log looks like:

[INFO][fcc ]: key_config_manager.c:159:kcm_item_store:===> item name =  mbed.UseBootstrap len=17, data size=4
[INFO][fcc ]: key_config_manager.c:101:kcm_init:===>
[DBG ][fcc ]: storage.c:72:storage_init:===>
[INFO][esfs]: esfs_init - enter
[DBG ][fcc ]: storage.c:77:storage_init:<===
[INFO][fcc ]: key_config_manager.c:118:kcm_init:<===
[DBG ][fcc ]: key_config_manager.c:42:kcm_create_complete_name:===> name len=17
[DBG ][fcc ]: key_config_manager.c:65:kcm_create_complete_name:<=== kcm_buffer_size_allocated_out=  26
[DBG ][fcc ]: storage.c:258:storage_file_create:===> file_name_length=26
[INFO][esfs]: esfs_create - enter


Wait patiently; entropy collection on a freshly booted system can take up to 20 minutes. Alternatively, you can install and configure rng-tools to make the entropy collection faster.


The application is blocked while waiting for the entropy to be collected. The random reading from /dev/random or /dev/hwrng is a blocking call, and the reading will not take place until sufficient entropy is collected.

Note: This also applies to Device Management Edge.