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Old 05.11.2012, 13:50
xtrm xtrm is offline
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Thumbs up [GUIDE] How to solve most download CRC errors

I have been dealing with some download CRC errors and successfully solved the problem. I would like to share some tips and ask you about more ways to fix them.

1. Add Jdownloader files to exclusion list of Antivirus, firewall and HIPs software:
- Add the following files to the exclusion list:
JDownloader.exe, JDownloader.jar, JDownloaderBETA.exe, JDownloaderD3D.exe, JDownloaderPortable.exe, JDUpdate.exe ..
This step must be done in any of your antivirus, firewall or HIPs installed in your system. It may prevent possible lock ups while trying to write a lot of data in your hdd.

2. Limit your download speed by setting it to a bit less than your maximum download speed:
- Go here in order to check your maximum theorical download speed, and then set a limit in your jdownloader, with a bit less, about 10% less than your maximum download speed.
In example, if you maximum download speed is 5000kb/s, set it to 4400kb/s.
This setting could prevent packets to be lost because of network lock up, with a free space for the retransmision of packets and network data which will grant a secure download.

3. Check your hard disk state and defragment:
Its a good way of avoiding a lot of CRC errors. Check that your disk is in good state and fragmentation is very low. You can use the free wonderfull program defraggler to analyse your disk and defragment your files:
piriform.com/defraggler
It may prevent to get corrupted downloads since most of the data will be downloaded in secuential sectors, and will avoid to move and write a lot of downloaded data in random locations. Make a backup of important things before beginning defragmentation.
*DO NOT defragment a SSD hard disk. Its not necessary and you can lost all your data.
*I would recommend not downloading data directly to a green 5400rpm hard disk. Those disks are known to be very slow and have bad stability (but just my thoughs).

Check that your HDD has good health and is working in the right Mode with tools like HD Tune Pro or AIDA64. In old computers you could find the old "PIO working mode" which is also known to be very slow and could be the cause of unknown hardware interrupts. Set working mode to Ultra DMA whenever its possible. (If you have hardware interrupts, Microsoft Windows Performance xperf is a good tool to detect the cause (driver) of unknown hardware interrupts seen with Process Explorer).

4. Make sure you have enough free disk space, about 20% of your total disk capacity.
This setting could be more or less depending of your total unit disk capacity, but make sure you have enough free GB all the time. Never leave the disk partition without free disk space.

5. Check your internet connection for network stability and errors:
Go to start, run, cmd.exe, right click on cmd.exe, RUN as Admin. Execute the following command line:
Quote:
C:\>ping -t -l 1460 uploaded.net > network.txt
This will write a file called network.txt in c: drive, where you will be able to see if there are errors or packet losts.
A good report will have the following appearance, with 0 packet lost:
Code:
Haciendo ping a www.uploaded.net [95.211.143.200] con 1460 bytes de datos:
Answer from 95.211.143.200: bytes=1460 time=56ms TTL=49
Answer from 95.211.143.200: bytes=1460 time=55ms TTL=49
Answer from 95.211.143.200: bytes=1460 time=56ms TTL=49
Answer from 95.211.143.200: bytes=1460 time=55ms TTL=49
Answer from 95.211.143.200: bytes=1460 time=55ms TTL=49

If you have network errors you will get a lot of bad CRC downloads and you may also check for your router temperature, cables or even computer hardware. Reset any of them, change cables, check temps, press them...

6. Make sure you have the lastest stable version of JDownloader and the right Java version.

7. Delete temporary files and correct possible errors with ATFCleaner, CCleaner and Spybot SD.

8. Check for more usefull tips about CRC errors at this thread:
http://board.jdownloader.org/showthread.php?t=9308

9. Check your memory modules for errors:
The best way to test for memory is with memtest 86+ (4.2.0). Download it, burn iso to a CD, and check all your modules for errors. If your modules doesnt have any errors, it will a good way of preveting a lot of CRC errors.
Degradation of memory modules after some years is a very common issue because of electricity, electromigration, temperature.. ( lowlevelhardware.blogspot.com.es/2012/04/electromigracion-en-microprocesadores.html )
memtest.org/#downiso
Its recommended to replace the damaged modules with new ones of the same model and speed. If you cant find them because your mem modules are old, replace all your modules. Better to buy memory with low voltage and low timings

10. If you still get CRC errors, go to JDownloader and set MAX concurrent connections to 1 (Max. Con.), and set MAX downloads to 1 (Max. Dls.).
This setting could prevent possible hard disk IO lock ups and some background programs scanning too much downloaded data. Also downloading a file without concurrent download chunks, will be a safe mode to check for stability.

11. If you still get CRC errors, try excluding all java.exe. I would personally not recommend this setting since it may leave your system totally unprotected to remote java exploits, which are very common these days. Just do it only for testing stability:
Exclude:
c:\windows\system32\java.exe
c:\program files\java\jre6\bin\java.exe
c:\program files\java\jre6\bin\javaw.exe
c:\program files\java\jre7\bin\java.exe
c:\program files\java\jre7\bin\javaw.exe

There are probably a lot more steps to be done in order to avoid CRC errors, feel free to add, comment or correct anything you see in this guide. Thanks

Last edited by xtrm; 14.05.2013 at 22:51. Reason: Corrected some phrases for better understanding.
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  #2  
Old 05.11.2012, 14:14
xtrm xtrm is offline
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Some suggestions for developers:
- Add a safe mode to start JDownloader with safe settings with full error log.
- In the future, it will be nice if there could be added some protection mechanism to check for corrupted data before the whole file has been downloaded. A safe mode could download a file with half of the speed, but checking the data two or more times with a lot of small concurrent downloads. This feature probably will be only possible for premium users and only in hosts which support concurrent chunck downloads.
- Dont know if this is already coded in JDownloader, but there are some secure network algorithms to prevent corrupt downloads and redownload only the bad parts. I know basic protection checksum is already implemented in TCP protocol, but it will be wonderfull to add an internal more secure algorithm to prevent bad downloads and download only the bad corrupted parts. (Having to redownload a corrupted 2GB file is a pain).

-------------------

Just to add that JDownloader nowadays is a lot better and much more stable. There are less CRC errors and I have seen improvements in connections to servers and download managing. The tips above wont be probably needed but its always a good resource to check for common solutions.

Last edited by Lram32; 07.12.2013 at 03:05. Reason: merged posts
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  #3  
Old 31.10.2013, 11:48
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raztoki raztoki is offline
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considering stable has been out for 4+ years and last nightly 3+ years, unless your using JD2, nothing has changed at all in JDownloader core which would influence your findings. It would be more so external factors, are these configured correctly? security software is known to introduce CRC issues.
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Last edited by raztoki; 15.06.2017 at 03:11. Reason: grama
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  #4  
Old 07.12.2013, 02:13
squirtmph squirtmph is offline
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Post thank you!

thank you very much for fine post, Sir.

i have to do allot those setting myself now!
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  #5  
Old 29.03.2014, 04:49
squirtmph squirtmph is offline
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Default Incredible Post

I like to thank you for such well done tutorial posted! thank you for helping myself and other to learn more with such nice software!
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Old 27.01.2015, 07:09
WillHolt
Message deleted by raztoki. Reason: off topic
  #6  
Old 14.06.2017, 21:17
imagetypers imagetypers is offline
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Is this post/steps still applicable?
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  #7  
Old 15.06.2017, 03:37
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raztoki raztoki is offline
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@imagetypers

from the OP
topic 1, 5, 6, 9 are relevant.

10 but not for the reasons he stated, but related to issue 1 (so duplicated point/topic). Over the years we have had reports that chunking increases the crc corruption. As virus scanners couldn't deal with chunked data, they wanted everything in single chunk to scan from position beginning to to end in which a single chunk provides. I'm not aware of any chunking bugs in JDownloader that caused crc corruption. Typically chunking will not increase data corruption by its use.

8, probably doesn't apply now as many new versions our out since. But goes to show that issue 1 is very important.

7 deleting temp files wont influence data corruption, and "possible errors"**, very vague...

4 misconception, this never happens. Full harddrive just means no where to save. It can't save data onto components that are already full... kinda also related to issue 3. full harddrive usually means downgraded performance on write cycles.

3 I don't agree with defragging statements. fragmented harddrdive doesn't increase crc. Defragging actually increases read/write performances by moving related data closer together so the head of the physical harddrive doesn't have to seek as far during normal access. The trade offs with having nearly full harddrive is it has limited scope to where to store data. Thus more fragmentation occurs with full harddrive and performance downgrades. Defragging regularly also has downsides as it wears your device out for example; each sector on the harddrive has limited write cycles (same with SSD). If you read the warranty of the drive it will tell you typically lifespan via used hours.

2 I don't agree with this, your network hardware has QoS along with your operating system. This provides ability to share bandwidth based on pre determined algorithms. Some hardware lets you define this also. In the scheme of things, JDownloader transfers mostly over tcp/ip in which has built in error handling which deals with limited data corruption. Best practice is not to set connection settings within JDownloader higher than required (test to see the least amount of connections to max out bandwidth, for example if you have 1mbit internet, you don't need 20 chunks * 20 max sl dl = 400 downloads, you probably need 1 chunk * 1 download), otherwise this can fight hardware' QoS functions and other devices on the network or even on the same system do not get enough bandwidth and connections can suffer socket related issues.

I would expand on 9
not just memory (RAM), it can be related to other hardware like network hardware and network drivers or harddrives failing. This is quite common believe it or not.

raztoki
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Last edited by raztoki; 15.06.2017 at 03:39.
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  #8  
Old 04.08.2017, 13:19
hwoarang5 hwoarang5 is offline
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i like to add, i been battling lately with random crc errors, unable to find solution until i accidentally disable my Kaspersky internet security, its a firewall and antiviral solution, even i white listed jdownloaded it somehow randomly causes my files to have crc errors, its freaking me out, i tested my hdd , ram several times, only to find out its this crapware... just disable or uninstall this when u downloading for a peace of mind.
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  #9  
Old 04.08.2017, 13:23
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raztoki raztoki is offline
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@hwoarang5
yes 1) is the cause to most crc issues in my observation, and then faulty hardware.
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  #10  
Old 12.08.2017, 05:23
hwoarang5 hwoarang5 is offline
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After bit more testing its a combination of software that cause my crc error, when i run kaspersky and EA's origin client in background i get this, tested with 100% recreation results.

Origin client - off , Kaspersky - on = No error no matter what i set on my download speed, number of connection

Origin client and Kaspersky - off = same as above

origin client -on, Kaspersky - off, = randomly i still get crc error, if set high speed or connection ,it get worse

Steam, discord were also tested ,no problem on those.
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  #11  
Old 12.08.2017, 05:57
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raztoki raztoki is offline
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those gaming clients, are used to prevent you from cheating right?
so they could be accessing memory and checking what's its been used for/by ?
maybe causing issue, it be one of the first times I've heard it being the cause though.

raztoki
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  #12  
Old 01.09.2017, 06:50
Eenptish Eenptish is offline
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wow,nice guide
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