Proper mask
Hi there!

I'm a totally newbie so I'm asking for you help...

I have a md5-file with passwords "????-????-????-????", where ? is 0123456789ABCDEF.

So I'm trying to bruteforce via a mask:
>hashcat64 -m 0 -a 3 -i --increment-min=19 --increment-max=19 work.md5 ?H?H?H?H-?H?H?H?H-?H?H?H?H-?H?H?H?H
hashcat (v5.1.0) starting...

* Device #1: WARNING! Kernel exec timeout is not disabled.
            This may cause "CL_OUT_OF_RESOURCES" or related errors.
            To disable the timeout, see:
OpenCL Platform #1: NVIDIA Corporation
* Device #1: GeForce GTX 1080 Ti, 2816/11264 MB allocatable, 28MCU

Hashes: 99 digests; 99 unique digests, 1 unique salts
Bitmaps: 16 bits, 65536 entries, 0x0000ffff mask, 262144 bytes, 5/13 rotates

Applicable optimizers:
* Zero-Byte
* Early-Skip
* Not-Salted
* Not-Iterated
* Single-Salt
* Brute-Force
* Raw-Hash

Minimum password length supported by kernel: 0
Maximum password length supported by kernel: 256

ATTENTION! Pure (unoptimized) OpenCL kernels selected.
This enables cracking passwords and salts > length 32 but for the price of drastically reduced performance.
If you want to switch to optimized OpenCL kernels, append -O to your commandline.

Watchdog: Temperature abort trigger set to 90c

Integer overflow detected in keyspace of mask: ?H?H?H?H-?H?H?H?H-?H?H?H?H-?H?H?H?H

Started: Wed Jul 10 02:38:06 2019
Stopped: Wed Jul 10 02:38:12 2019

How to fix the overflow error? Or is not a feasible task even for md5?

Thank you!
if you calculate how many passwords you are trying you will see that you are getting 16 to the power 16 or 18446744073709551616 passwords (18 billion billion).

On this post you can see that 2x tesla v100 can do 100.1 GH/s for MD5. It would take that system 6 years to run through this space (assuming it can maintain a steady pace of 100 GH/s).

What you are searching is just too big, there is no way to fix the overflow error. The only thing you can do is test smaller ranges.