Unable to upload photos Error: Uploaded Folder missing or not readable/ writeable !

[Grantelhuber]

I installed Lychee on my Raspberry Pi webserver but when attempting to upload photos either via import from server or from link i always get the error message "An upload-folder is missing or not readable and writeable! Please take a look at the console of your browser fo further details." when checking the console i iam told that something is wrong with main.js :

"Objectdescription: "Upload failed. Server returned an error!"params: XMLHttpRequest {onreadystatechange: null, readyState: 4, timeout: 0, withCredentials: false, upload: XMLHttpRequestUpload, …}response: "Error: An upload-folder is missing or not readable and writable!"proto: Objectconstructor: ƒ Object()hasOwnProperty: ƒ hasOwnProperty()isPrototypeOf: ƒ isPrototypeOf()propertyIsEnumerable: ƒ propertyIsEnumerable()toLocaleString: ƒ toLocaleString()toString: ƒ toString()valueOf: ƒ valueOf()defineGetter: ƒ defineGetter()defineSetter: ƒ defineSetter()lookupGetter: ƒ lookupGetter()lookupSetter: ƒ lookupSetter()get proto: ƒ proto()set proto: ƒ proto() lychee.error @ main.js:5"

what can i do pls help me i want to get this working and i have tried so long.