I have started to get more and more error with this error message ...

<core_client_version>7.14.2</core_client_version>
<![CDATA[
<message>
(unknown error) - exit code -1073740791 (0xc0000409)</message>
<stderr_txt>
Factorization '0' is incorrect: 0 is not a prime

</stderr_txt>
]]>

example task with this error:
https://sech.me/boinc/Amicable/result.php?resultid=29107105

Applies to computers with both Windows and Linux system, with CPU and CPU / GPU running.
Have paused my work for Amicable Numbers until I can find a solution.

Did a quick search at google and Amicable Numbers forum for the problem but found none of interest.

What can I do to sort it out ?

This error happens when saved progress ("amicable_checkpoint" file) contains incorrect data or was corrupted somehow. If you get this error again, please check "amicable_checkpoint" in the app directory and post it here.

I have a similar issue. Many workunits go up to 99%, then percentage drop to a very low value and stay there. If I suspend and resume, they end with error.
I checked amicable_checkpoint when percentage was 98 and after too. It says this:

0 0#

https://sech.me/boinc/Amicable/result.php?resultid=31448292

<core_client_version>7.16.6</core_client_version>
<![CDATA[
<message>
process exited with code 193 (0xc1, -63)</message>
<stderr_txt>
Factorization '0' is incorrect: 0 is not a prime
SIGABRT: abort called
Stack trace (10 frames):
[0x437140]
[0x457be0]
[0x457ac9]
[0x52b2ea]
[0x405696]
[0x4067c0]
[0x4009a4]
[0x51ab66]
[0x51ad5a]
[0x426549]

Exiting...

</stderr_txt>
]]>

I removed the app_config.xml I was using to set the number of mt cores and let the settings from the site do the job. I don't know if this is related but I haven't had any problems since.