Ardoino not working properly when the code memory size is larger than 16kb, the device has a 32k programmable memory.
Iam using Atmega328, I also use RedBoard and I had the same problem.
How much SRAM are you using? Are there a lot of big arrays, a lot of print statements?
Running out of SRAM causes issues before running of flash memory space.
Iam using 2kb SRAM memory.
This problem happens projects which are with lcd screens and LED matrices Which have big arrays ??of letters and bitmap.
Now the problem became clearer ... but I can fix it?
but I can fix it?
Only you can answer that.
I don't really see this as an installation or troubleshooting topic, but the without any code, it isn't really a programming topic either.
I'll move it to project guidance.
If there are any big arrays that you're reading and not writing, PROGMEM them.
http://www.nongnu.org/avr-libc/user-manual/group__avr__pgmspace.html