Getting same error twice
You have two GND nets: GND and GND1. And the same problem for both of them. So this is not the same error but two errors.
If KiCad behavior would depend on laptop at which it runs it would be vary bad about that program.
Read:
Your power symbols need a PWR_FLAG. Read in the manual how these work.
Can you please tell me where to add Power flag, i am beginner in kicad
Where at schematic sheet is your choice. I donât like them so I donât use them at all.
How to connect them? - you have an example in link I gave you. Open it and press PgDn once.
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As your 5V battery provides power, you should probably place it on positive and negative terminal of the battery. The power flag check is just making sure youâre powering the board properly. KiCad is stupid and doesnât know that the battery will output power, but it canât be sure because your circuit could also charge or test the battery or whatever.
You should probably only use a single GND symbol, GND and GND1 will not connect.
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Itâs very difficult to just âTellâ someone where to put PWR_FLAG as it really does depend on the way you lay out a schematic and thatâs a personal preference although there are general rules or âguidelinesâ so it is best to read about PWR_FLAGS and fully understand them and it will make sense in the end 
. Looks like your trying to make a simple amplifier of sorts and I think you are trying to keep signal and power separate perhaps?? anyhow this is good practice in some circuits but for this one it has just caused confusion 
I would just stick to one ground net. If U1 is a regulator check itâs datasheet for correct input/output layout. Good luck with your project 
Itâs relatively simple:
A Power Input needs to be connected to a Power Output somewhere.
The GND symbol is logically a power input.
Your circuit has no power outputs anywhere, so you get the error. The solution is to use the PWR_FLAG, this provides a power output for your GND power inputs.
A solution is simply to put it on the sheet like this:
A more advanced example is this one:
Note that the â+5 Vâ and â0 Vâ outputs have a PWR_FLAG, because theyâre not connected to any power outputs.
â-5 Vâ has no PWR_FLAG. Why? Because pin 5 of the LM2660 is a power output.
Hope this helps.
PS: in your case, Iâd place a PWR_FLAG on the positive and the negative terminal of your battery.
This whole PWR_Flag is just nonsense and antiquated.
Devs please sort this out or, at the very least, automate it or hide it away.
It is easy to hide it away if you want, by disabling that particular ERC in Schematic Setup.
It is not possible to otherwise âsort outâ by changing the code: the whole point of this check is to nudge you (the designer) to check that your circuit is actually properly powered somehow, and mark where power is coming in. This canât be automated, there is no way for software to know that you are connecting a certain connector to a power source. If this nudge (and this check) is not valuable to you, just disable it.
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But there is a way for software to know that if IC is powered through ferryte bead from net with power on it than at power input pin of IC power is also present.
Not at the moment, because the software doesnât know what a ferrite bead is, or that it represents a low-impedance connection between its two pins.
KiCad could add some way for you to flag that a particular ferrite bead is a low-impedance connection, but it would still be a step you the designer have to do, like PWR_FLAG.
But only once - when defining symbol in library.
But it is not my problem - I donât use ERC.
But (one more but) it is hard to count how many times the PWR_FLAG subject has been covered here at forum. Once a month is probably too low an estimate.
If we divide new KiCad users into these who read âGetting startedâ and these who donât read it than probably each one from second group came here with that question/problem.
It leads to think that may be considering to switch this check in ERC by default off is not the worst idea.
I just donât know. The better would be probably to add flag in symbol that could mean that all pins of this symbol are connected together for DC and switch this flag on for all L symbols reducing the number of necessary PWR_FLAGs at schematics.
Connecting inputs to outputs is really hard, I know. Adding power on top needs AI, it seems. 
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