MX300 Performance issues - Error Code -36 (Mac OS Mojave)

Kilobyte Kid

MX300 Performance issues - Error Code -36 (Mac OS Mojave)

I have a 2tb MX300 which is repeatedly showing error code 36 when I am trying to backup my 700gb music folder. I am becoming quite alarmed at my inability to back up this folder since this error code seems to lead me to believe that the drive is failing.


 The error is thought to be a result of moving data back and forth between Mac & windows file system. I am noticing the error on files which I have downloaded from the internet without transferring to a second file system.

The possible solutions I have tried are those which are prescribed as standard for this type of error. I have removed the .ds_store files which are thought to cause this issue, but that has not resolved it. I can copy the file to the same internal disk, but not to any external disk. Nor can I upload it to any online service.


I have previously been able to copy the file in particular, but can no longer do that. I have previously run into the problem but deleted the files because I thought they were corrupted. Now EVEN MORE files are showing this error, this leads me to believe it is the drive. 


Are there any troubleshooting steps I can try before I send this thing back? 

9 Replies

Re: MX300 Performance issues - Error Code -36 (Mac OS Mojave)

Provide a screenshot of the SMART Attributes from DriveDX.   Also what firmware is the MX300 using?


Do the filenames have non-alpha-numeric characters that might be causing the problem?


Are you using APFS or HFS+ on the MX300?


Have you run First Aid from Disk Utility?


What is the model of your computer?  I need the complete model listed in "About This Mac".

Kilobyte Kid

Re: MX300 Performance issues - Error Code -36 (Mac OS Mojave)

Hi HWTech, thanks so much for your reply.


I've downloaded Drive Dx and it looks like it's found some issues. I've pasted the main screen, is there a further section you would like me to focus on?

 Screen Shot 2018-12-04 at 3.26.52 pm.png


I clicked on the diagnosis button and got this screen:

Screen Shot 2018-12-04 at 3.33.00 pm.png


As instructed by the app, I then did a self-test (twice) and came up with this:

Screen Shot 2018-12-04 at 3.34.22 pm.png



There are no non-alpha numeria characters, and I'm using APFS. I'm not sure how to check the firmware, but I purchased it in September 2017.


I have run First-Aid utility and it found no problems. Please see screenshot of the details of my mac:

Screen Shot 2018-12-04 at 3.25.12 pm.png


I have to be honest, I am getting more than a little freaked out by this. The thought of losing my music collection is absolutely devastating. I will be waiting on your reply.



Re: MX300 Performance issues - Error Code -36 (Mac OS Mojave)

I cannot see your screenshots since they haven't been approved by the moderators yet, but I need to see the actual SMART Attributes listed with their values.  You should be able to find the firmware revision of the SSD within DriveDX somewhere.  When it comes to SSDs & third party apps, don't always trust them to properly show the summary health status.   Many apps treat SSDs like hard drives and this can give an inaccurate health assessment.  I've seen DriveDX do this before.



Kilobyte Kid

Re: MX300 Performance issues - Error Code -36 (Mac OS Mojave)

Yes, I'm sorry--I didn't realise they contained my serial number, it was removed overnight. Thanks again for your help.


I see now the firmware is M0CR040.


I'm not sure how to find the SMART stuff you requested, I've been through the sections on the app and it doesn't look like there is any more detailed info. I'll paste the report:



Report Timestamp : 5 December 2018 9:00:01 am AEDT
Report Timestamp (ISO 8601 format) : 2018-12-05T09:00:01

Application Name : DriveDx
Application Version :
Application SubBuild : 1
Application Edition : Standalone
Application Website :
DriveDx Knowledge Base Revision : 9/9

Computer Name : 
Host Name : 
Computer Model : Macmini6,1

OS Boot Time : 2018-12-03T12:18:21
Time Since Boot : 1 day 20h 41m 40s
OS Name : macOS
OS Version : 10.14.1
OS Build : 18B75
OS Kernel Version : Darwin 18.2.0

SAT SMART Driver Version : N/A
ATA Command Support Tolerance : verypermissive
N of drives in report : 1


### DRIVE 1 OF 1 ###
Last Checked : 5 December 2018 8:56:51 am AEDT
Last Checked (ISO 8601 format) : 2018-12-05T08:56:51

Advanced SMART Status : FAILING
Overall Health Rating : N/A 99.0%
Overall Performance Rating : GOOD 100%
SSD Lifetime Left Indicator : GOOD 99.0%
Issues found : 4

Serial Number :
WWN Id : 5 00a075 11765a216
Volumes : jpoeqwewpoq
Device Path : /dev/disk0
Total Capacity : 2.1 TB (2,050,408,636,416 Bytes)
Model Family : Crucial/Micron MX300 SSD
Model : Crucial_CT2050MX300SSD1
Form Factor : 2.5 inches
Firmware Version : M0CR040
Drive Type : SSD

Power On Time : 417 hours (17 days 9 hours)
Power Cycles Count : 1,628
Current Power Cycle Time : 44.7 hours


S.M.A.R.T. support enabled : yes
DriveDx Active Diagnostic Config : Crucial (Micron) MX300 SSDs config [ssd.micron.crucial.mx300]
Sector Logical Size : 512
Sector Physical Size : 512
Physical Interconnect : SATA
Logical Protocol : SATA
Removable : no
Ejectable : no
ATA Version : ACS-3 T13/2161-D revision 5
SATA Version : SATA 3.2, 6.0 Gb/s (current: 6.0 Gb/s)
Bay # : 1
I/O Path : IOService:/AppleACPIPlatformExpert/PCI0@0/AppleACPIPCI/SATA@1F,2/AppleIntelPchSeriesAHCI/PRT0@0/IOAHCIDevice@0/AppleAHCIDiskDriver/IOAHCIBlockStorageDevice
Attributes Data Structure Revision : 16
SMART Command Transport (SCT) flags : 0x35
SCT Status supported : yes
SCT Feature Control supported : yes
SCT Data Table supported : yes
Error logging capabilities : 0x1
Self-tests supported : yes
Offline Data Collection capabilities : 0x7b
Offline Data Collection status : 0x0
Auto Offline Data Collection flags : 0x0
[Known device ]: yes
[Drive State Flags ]: 0x4000300
[Last State Change Timestamp ]: 2018-12-05T08:56:51
[Last State Change Flags ]: 0x4000300
[Last State Change Diff Flags ]: 0x2c00
Last Email Report Timestamp : 2018-12-05T08:56:51
Last Email Report Reason Flags : 0x4000300
Last Email Report State Change Flags : 0x2c00

Data Read : 574.1 GB
Data Written : 66.8 GB
Data Read/Write Ratio : 8.59
Average Throughput (Read) : 6.2 MB/s
Average Throughput (Write) : 12.2 MB/s

Operations (Read) : 12,435,749
Operations (Write) : 3,127,492
Operations Read/Write Ratio : 4
Throughput per operation (Read) : 48.4 KB/Op
Throughput per operation (Write) : 22.4 KB/Op

Latency Time (Read) : 0 ns
Latency Time (Write) : 0 ns
Retries (Read) : 0
Retries (Write) : 0
Errors (Read) : 111
Errors (Write) : 0

Failed Indicators (life-span / pre-fail) : 0 (0 / 0)
Failing Indicators (life-span / pre-fail) : 2 (2 / 0)
Warnings (life-span / pre-fail) : 0 (0 / 0)
Recently failed Self-tests (Short / Full) : 1 (1 / 0)
I/O Error Count : 111 (111 / 0)
Time in Under temperature : 0 minutes
Time in Over temperature : 0 minutes

5 Reallocated NAND Block Count 58 100% Failing
172 Erase Fail Count Total 0 100% OK
173 Average Block Erase Count 16 99.0% OK
180 Unused Reserve (Spare) Blocks 9,149 100% OK
247 Host Program Page Count 658,982,838 (9.8 TB) 100% OK
248 Background Program Page Count 1,160,927,256 (17.3 TB) 100% OK

Current Temperature : 32
Power Cycle Min Temperature : 27
Power Cycle Max Temperature : 49
Lifetime Min Temperature : 18
Lifetime Max Temperature : 53
Recommended Min Temperature : 0
Recommended Max Temperature : 70
Temperature Min Limit : -5
Temperature Max Limit : 75

1 Raw Read Error Rate Pre-fail online 0x1D 100 50 100 5/12/18 8:56 am 100% OK
5 Reallocated NAND Block Count Life-span online 58 100 10 100 5/12/18 8:56 am 100% Failing
9 Power On Hours Life-span online 417 100 0 100 5/12/18 8:56 am 100% OK
12 Power Cycle Count Life-span online 1,628 100 0 100 - 100% OK
171 Program Fail Count Total Life-span online 2 100 0 100 - 100% OK
172 Erase Fail Count Total Life-span online 0 100 0 100 - 100% OK
173 Average Block Erase Count Life-span online 16 99 1 99 - 99.0% OK
174 Unexpected Power Loss Count Life-span online 31 100 0 100 - 100% OK
180 Unused Reserve (Spare) Blocks Pre-fail online 9,149 0 0 0 5/12/18 8:56 am 100% OK
183 SATA Downshift Count Life-span online 0 100 0 100 - 100% OK
184 Error Correction Count Life-span online 0 100 50 100 - 100% OK
187 Reported Uncorrectable Errors Life-span online 37,792 100 0 100 5/12/18 8:56 am 100% Failing
194 Temperature (Celsius) Life-span online 32 68 25 47 5/12/18 8:56 am 57.3% OK
196 Reallocated Event Count Life-span online 58 100 0 100 5/12/18 8:56 am 100% OK
197 Current Pending Block Count Life-span online 0 100 0 100 5/12/18 8:56 am 100% OK
198 Offline Uncorrectable Block Count Life-span offline 2 100 0 100 - 100% OK
199 UDMA CRC Error Count Life-span online 0 100 0 100 - 100% OK
202 Percent Lifetime Remaining Life-span offline 1 99 1 99 - 99.0% OK
206 Write Error Rate Life-span online 2 100 0 100 - 100% OK
210 Successful RAIN Recovery Count Life-span online 74 100 0 100 - 100% OK
246 Total Host Sector Writes Life-span online 21,087,392,869 (9.8 TB) 100 0 100 5/12/18 8:56 am 100% OK
247 Host Program Page Count Life-span online 658,982,838 (9.8 TB) 100 0 100 5/12/18 8:56 am 100% OK
248 Background Program Page Count Life-span online 1,160,927,256 (17.3 TB) 100 0 100 5/12/18 8:56 am 100% OK


5 0 hours UNC READ DMA EXT
4 0 hours UNC READ DMA EXT
3 0 hours UNC READ DMA EXT
2 0 hours UNC READ DMA EXT

1 416 Short offline 10% Completed: read failure 2298768
2 416 Short offline 10% Completed: read failure 2298768



[0x01] General Statistics (revision 1)
0x08 Lifetime Power-on Resets : 1,628
0x10 Power-on Hours : 417 hours
0x18 Logical Sectors Written : 21,087,392,869 (9.8 TB)
0x20 Number of Write Commands : 666,302,818
0x28 Logical Sectors Read : 35,869,340,959 (16.7 TB)
0x30 Number of Read Commands : 371,499,731

[0x04] General Errors Statistics (revision 1)
0x08 Number of Reported Uncorrectable Errors : 37,792
0x10 Resets Between Cmd Accept. and Compl. : 2,017

[0x05] Temperature Statistics (revision 1)
0x08 Current Temperature : 32 °C
0x10 Average Short Term Temperature : 42 °C
0x20 Highest Temperature : 53 °C
0x28 Lowest Temperature : 18 °C
0x30 Highest Avg. Short Term Temperature : 42 °C
0x38 Lowest Avg. Short Term Temperature : 42 °C
0x50 Time in Over-Temperature : 0 minutes
0x58 Specified Max Operating Temperature : 70 °C
0x60 Time in Under-Temperature : 0 minutes
0x68 Specified Min Operating Temperature : 0 °C

[0x06] Transport Statistics (revision 1)
0x08 Number of Hardware Resets : 6,848
0x10 Number of ASR Events : 17
0x18 Number of Interface CRC Errors : 0

[0x07] Solid State Drive Statistics (revision 1)
0x08 Percentage Used Endurance Indicator : 1.0 %




Re: MX300 Performance issues - Error Code -36 (Mac OS Mojave)

 Your output included the information, but unfortunately is hard to read in its current format.  The section with the SMART Attributes is labeled "Health Indicators".   If I'm reading it correctly, you had 58 reallocated blocks, but had almost 38K Uncorrectable Errors which likely occurred when the SSD didn't properly reallocate those 58 bad blocks in a timely manner.  I don't believe you had 38K different errors, but a few errors which repeated until the blocks were reallocated.   I encountered the same issues with our MX300s using the older firmware.  After updating the firmware and Secure Erasing them our SSDs have been fine as far as I know.   Those Uncorrectable Errors may have corrupted some of your data.   It is normal behavior for SSDs to get bad blocks from time to time as long as the blocks are reallocated before they produce the Uncorrectable Errors which reach the filesystem & data.  Unfortunately the older firmwares had issues here.  The good news is there are no blocks pending reallocation.   You will want to keep an eye on Attributes 5,  187,  196, 197, and 198 and if you see any of them continuing to increase then errors are still accumulating.  Attributes 187 & 198 are ones where they reach the filesystem,  The others shouldn't affect your data.



You are running really old firmware.   You definitely want to update the firmware.  Anything before M0CR060 had issues.  Supposedly M0CR070 was recently released, but I'm not sure it is available yet through the manual download/update process.   Maybe if you update the firmware you will have better luck.  The firmware update isn't supposed to affect the data, but there is always a risk if something unexpected occurs.


You could try using Carbon Copy Cloner as it has the ability to ignore errors and it will log which files could not be transferred.  There are free data recovery utilities called "TestDisk" & "Photorec" (both are made by the same group) that might allow you to copy the data.   Another option is a command line utility called Gnu ddrescue (there is another one which isn't as good, the "Gnu" part is important) which can "clone" the partition to another drive or raw image file where you could then pull rescued data, but you need to run it from another drive.  I've used it with great success with Linux, but not as much under OSX due to the way Apple handles things.   

Kilobyte Kid

Re: MX300 Performance issues - Error Code -36 (Mac OS Mojave)

Hey, thanks again for your help. 


Here's the screenshot of the Health Indicators page:

Screen Shot 2018-12-06 at 11.59.41 am.png


To sum your advice, I should try the following steps:

1. Use Carbon Copy Clone to clone the drive

2. Update firmware to latest

3. Secure format

4. Reinstall OS/Reinstate carbon copy



Everything else I use is in the cloud except for the music, so I would only clone that. Reinstalling the OS is not a big deal, but I would prefer not to since it means erasing the music collection without only the cloned copy as a backup.


I do use Time Machine backup, but not in about a month or so. I'm uncertain as to it's reliability (I've heard some things).


Re: MX300 Performance issues - Error Code -36 (Mac OS Mojave)

If you've been using the SSD since you posted the text output of DriveDX and the screenshot of the SMART Attributes, then it appears no new errors have occurred in any form which is good news.  You are probably just dealing with some filesystem corruption now.  Unfortunately I'm not aware of any other utility at this time that can be used to attempt repairing the APFS filesystem.



Step 3 should be Secure Erase and the SSD will need to be installed internally on your computer.  To Secure Erase the SSD on the Mac, try using PartEd Magic.   Create the PartEd Magic bootable USB drive using Etcher.  If PartEd Magic won't work for you, then I could provide instructions using a Linux boot disk which involves a few commands in a Terminal.


Step 4:  If you clone the drive to another physical drive and not an image file (.dmg), then you can use Migration Assistant on the first boot into the new OS to migrate everything from the clone to your SSD.  I'm not sure if Migration Assistant will allow you to mount and transfer from a .dmg image (doubtful).   If you don't/cannot use Migration Assistant, then you could either use CCC to transfer the files back or copy them manually.


I've never used Time Machine so I cannot help with it, but I've also heard some things as well.  You could give it a try as it might be an easy option if you cannot clone to another physical drive and use Migration Assistant.  If you have problems, you just go for one more reinstall.


Please let us know how you make out with the recovery and if you encounter any issues or have more questions, please feel free to ask.

Kilobyte Kid

Re: MX300 Performance issues - Error Code -36 (Mac OS Mojave)

Wait. So filesystem corruption?


How can you tell? Because there has been no new SMART errors? What about the ones that are already there?


To confirm, it isn't the drive?


Re: MX300 Performance issues - Error Code -36 (Mac OS Mojave)

Normally each block on an SSD is designed to handle multiple bit errors which are auto corrected behind the scenes.  Once the number of bit errors on a block reach the maximum which can be autocorrected, the SSD's controller is supposed to mark the block as bad and reallocate it.  With the older firmware, the MX300 doesn't reallocate the block in time and more bit errors occur which cannot be corrected and these new bit errors reach the filesystem.


Normally when a block goes bad on an SSD it should be automatically reallocated without the user or filesystem noticing.  Unfortunately the circumstances were not normal and the bad blocks took too long to reallocate so you started receiving Uncorrectable Errors (attributes #187 & #198) which did impact the filesystem and/or data since you are having issues copying some files.   Now all of the bad blocks have been reallocated which have stopped the Uncorrectable Errors so no more damage is occurring, but you do need to deal with the file copy errors.  Hopefully once you update the firmware on the MX300 you won't have the Uncorrectable Error issue again when the next block goes bad.


Now you just need to deal with the aftermath of the Uncorrectable Errors which involves a new filesystem with very limited tools to fix it.  Historically Disk Utility's First Aid has never been very good at repairing filesystem errors.  Unfortunately APFS is new and none of the usual third party filesystem repair utilities have been updated yet to repair APFS.  It is also possible it cannot be repaired anyway.


Looking back at your original post I see you could copy files to another spot on the SSD without issue.  This may be due to a new feature of  the APFS filesystem.  I don't know if this is the case, but I do know that it is possible to copy an item, but not really copy it.  You are just creating another link to the same item so in reality you are not actually touching the original file at all which is why it "worked". 

If it was my system, then after rescuing all the data I would first update the firmware, followed by a Secure Erase of the SSD to reset it.  Then I would boot the laptop into Internet Recovery mode to re-install macOS.  Then depending on the method used to rescue the data, I would restore it by manually copying it, using CCC to transfer files back or Migration Assistant if you cloned the whole drive to another physical drive. 


I would then investigate options for backing up the data.  I know backing up data reliably is difficult especially when there are large amounts of it, but it needs to be done and you also need to verify the data in the backups can be accessed & restored before something happens.  I've seen SSD's just die without warning many times (all vendors too) and the only way to recover data from them is to send it to a professional data recovery service.


Personally I feel the SSD will be fine, but you should monitor those SMART attributes from time to time just to be safe.  If you see more Uncorrectable Errors after the firmware update & Secure Erase, then you may want to exchange the drive under warranty.